Interleukin-22 polypeptides, nucleic acids encoding the same and methods for the treatment of pancreatic disorders

ABSTRACT

The present invention is directed to interleukin-22 polypeptides and nucleic acid molecules encoding those polypeptides. Also provided herein are vectors and host cells comprising those nucleic acid sequences, chimeric polypeptide molecules comprising the polypeptides of the present invention fused to heterologous polypeptide sequences, antibodies which bind to the polypeptides of the present invention and to methods for producing the polypeptides of the present invention.

The present application is a non-provisional application filed under 37C.F.R. 1.53(b)(1) which is a divisional of and claims priority to U.S.application Ser. No. 09/870,574 filed on May 30, 2001, which claims thebenefit of priority under 35 U.S.C. §120 to PCT/US00/23328 filed on Aug.24, 2000 and PCT/US00/14042 filed on May 22, 2000 which claims thebenefit of priority under 35 U.S.C. §119 to provisional application No.60/169,495 filed on Dec. 7, 1999, now abandoned.

FIELD OF THE INVENTION

The present invention relates generally to the identification andisolation of interleukin-22 (IL-22) and to methods of treatment ofpancreatic disorders.

BACKGROUND OF THE INVENTION

The pancreas is a large gland located behind the stomach and close tothe duodenum. It secretes digestive enzymes that enter the smallintestine via a duct. These enzymes facilitate the digestion ofproteins, fats and carbohydrates. In addition to the digestive enzymesthe pancreas also releases insulin and glucagon, which play an importantrole in sugar metabolism.

Pancreatitis is a disease in which the pancreas becomes inflamed. Damageto the pancreas occurs when digestive enzymes are activated and beginattacking the gland. In severe cases, there many be bleeding into thegland, tissue damage, infection and cyst formation. There are two formsof pancreatitis. An acute form which occurs suddenly and may be lifethreatening. A chronic form of pancreatitis may arise if the patientpersists in drinking alcohol, which results in the reduction ofpancreatic function and severe pain and weight loss. There areapproximately 50,000 to 80,000 cases of acute pancreatitis in the UnitedStates each year. It is more common in men than in women.

Currently, diagnosis of pancreatitis is difficult. Usually pancreaticfunction tests help the physician determine if there are enoughpancreatic enzymes being made. CAT scan can determine if there areabnormalities in the gland itself, such as gallstones, which arefrequently associated with this disorder. As chronic pancreatitis is aleading risk factor for pancreatic cancer, it should be treated as soonas the diagnosis is made.

The pancreas is comprised of about 80% acinar cells, 1%–2% islet cellsand 10%–15% of cuboidal ductal cells. Acinar cell carcinoma accounts for1%–2% of pancreatic carcinoma, with an additional 10%–15% of pancreaticcarcinoma comprised of acinar cells and other cell types [Nomura et al.,Ultra. Path. (1992) 16:317–329]. All of the causes of acute pancreatitisaffect the acinar cells in a way that results in the activation andretention of the digestive enzymes, which injure the acinar cell andcause the release of cytokines. The cytokines attract inflammatorycells, especially neutrophils, leading to further secretion ofcytokines. It is proposed that the released inflammatory moleculesinduce pancreatic edema, and local necrosis. Certain studies havesuggested that cytokine inhibtors may improve the course of pancreatitisin specific clinical settings.

Interleukin-22 (IL-22) is a newly identified cytokine produced byactivated T cells and is related to interleukin-10 (IL-10). IL-22signals through a receptor complex comprised of CRF2-4, also known asIL-10Rβ, and a new member of the class II cytokine receptor family,interleukin-22 receptor (IL-22R) [Xie et al., J. Biol. Chem. (2000) 275,31335–31339]. Of the members of this receptor complex, IL-10Rβ isexpressed in several tissues while the expression of IL-22R is fairlyrestricted, with high expression in the pancreas, suggesting that IL-22Ris controlling the site of action of IL-22. As an example, murine IL-22induces changes in gene expression in pancreatic acinar cells of severalgenes including pancreatitis associated protein (PAP1), a geneoverexpressed in acute pancreatitis [Iovanna et al, J. Biol. Chem.(1991) 266, 24664–24669]. IL-22 signaling through a receptor complexthat is highly expressed in pancreas, suggests that IL-22 may modulatean immune/inflammatory response in the pancreas, and may be involved indiseases of the pancreas including pancreatitis.

SUMMARY OF THE INVENTION

In one embodiment, the invention provides an isolated nucleic acidmolecule comprising a nucleotide sequence that encodes an interleukin-22(IL-22) polypeptide.

In one aspect, the isolated nucleic acid molecule comprises a nucleotidesequence having at least about 80% nucleic acid sequence identity,alternatively at least about 81% nucleic acid sequence identity,alternatively at least about 82% nucleic acid sequence identity,alternatively at least about 83% nucleic acid sequence identity,alternatively at least about 84% nucleic acid sequence identity,alternatively at least about 85% nucleic acid sequence identity,alternatively at least about 86% nucleic acid sequence identity,alternatively at least about 87% nucleic acid sequence identity,alternatively at least about 88% nucleic acid sequence identity,alternatively at least about 89% nucleic acid sequence identity,alternatively at least about 90% nucleic acid sequence identity,alternatively at least about 91% nucleic acid sequence identity,alternatively at least about 92% nucleic acid sequence identity,alternatively at least about 93% nucleic acid sequence identity,alternatively at least about 94% nucleic acid sequence identity,alternatively at least about 95% nucleic acid sequence identity,alternatively at least about 96% nucleic acid sequence identity,alternatively at least about 97% nucleic acid sequence identity,alternatively at least about 98% nucleic acid sequence identity andalternatively at least about 99% nucleic acid sequence identity to (a) aDNA molecule encoding an IL-22 polypeptide having the sequence of aminoacid residues from about 1 or about 33 to about 179, inclusive, of FIG.2 (SEQ ID NO: 2), (b) an amino acid sequence lacking the signal peptideof about amino acids 1 to X, wherein X is any amino acid from 29 to 38of FIG. 2 (SEQ ID NO:2) or any other specifically defined fragment ofthe full-length amino acid sequence as disclosed herein, or (c) thecomplement of the DNA molecule of (a).

In other aspects, the isolated nucleic acid molecule comprises anucleotide sequence having at least about 80% nucleic acid sequenceidentity, alternatively at least about 81% nucleic acid sequenceidentity, alternatively at least about 82% nucleic acid sequenceidentity, alternatively at least about 83% nucleic acid sequenceidentity, alternatively at least about 84% nucleic acid sequenceidentity, alternatively at least about 85% nucleic acid sequenceidentity, alternatively at least about 86% nucleic acid sequenceidentity, alternatively at least about 87% nucleic acid sequenceidentity, alternatively at least about 88% nucleic acid sequenceidentity, alternatively at least about 89% nucleic acid sequenceidentity, alternatively at least about 90% nucleic acid sequenceidentity, alternatively at least about 91% nucleic acid sequenceidentity, alternatively at least about 92% nucleic acid sequenceidentity, alternatively at least about 93% nucleic acid sequenceidentity, alternatively at least about 94% nucleic acid sequenceidentity, alternatively at least about 95% nucleic acid sequenceidentity, alternatively at least about 96% nucleic acid sequenceidentity, alternatively at least about 97% nucleic acid sequenceidentity, alternatively at least about 98% nucleic acid sequenceidentity and alternatively at least about 99% nucleic acid sequenceidentity to (a) a DNA molecule comprising the sequence of nucleotidesfrom about 58 or about 157 to about 594, inclusive, of the cDNA asdisclosed in FIG. 1 (SEQ ID NO: 1), or (b) the complement of the DNAmolecule of (a).

In a further aspect, the invention concerns an isolated nucleic acidmolecule comprising a nucleotide sequence having at least about 80%nucleic acid sequence identity, alternatively at least about 81% nucleicacid sequence identity, alternatively at least about 82% nucleic acidsequence identity, alternatively at least about 83% nucleic acidsequence identity, alternatively at least about 84% nucleic acidsequence identity, alternatively at least about 85% nucleic acidsequence identity, alternatively at least about 86% nucleic acidsequence identity, alternatively at least about 87% nucleic acidsequence identity, alternatively at least about 88% nucleic acidsequence identity, alternatively at least about 89% nucleic acidsequence identity, alternatively at least about 90% nucleic acidsequence identity, alternatively at least about 91% nucleic acidsequence identity, alternatively at least about 92% nucleic acidsequence identity, alternatively at least about 93% nucleic acidsequence identity, alternatively at least about 94% nucleic acidsequence identity, alternatively at least about 95% nucleic acidsequence identity, alternatively at least about 96% nucleic acidsequence identity, alternatively at least about 97% nucleic acidsequence identity, alternatively at least about 98% nucleic acidsequence identity and alternatively at least about 99% nucleic acidsequence identity to (a) a DNA molecule that encodes the same maturepolypeptide encoded by the human protein cDNA deposited with the ATCC onDec. 7, 1999 under the ATCC deposit number PTA-1031 (DNA125185-2806) or(b) the complement of the DNA molecule of (a).

Another embodiment is directed to fragments of an IL-22 polypeptidecoding sequence, or the complement thereof, that may find use as, forexample, hybridization probes, for encoding fragments of an IL-22polypeptide that may optionally encode a polypeptide comprising abinding site for an anti-IL-22 antibody or as antisense oligonucleotideprobes. Such nucleic acid fragments are usually at least about 10nucleotides in length, alternatively at least about 15 nucleotides inlength, alternatively at least about 20 nucleotides in length,alternatively at least about 30 nucleotides in length, alternatively atleast about 40 nucleotides in length, alternatively at least about 50nucleotides in length, alternatively at least about 60 nucleotides inlength, alternatively at least about 70 nucleotides in length,alternatively at least about 80 nucleotides in length, alternatively atleast about 90 nucleotides in length, alternatively at least about 100nucleotides in length, alternatively at least about 110 nucleotides inlength, alternatively at least about 120 nucleotides in length,alternatively at least about 130 nucleotides in length, alternatively atleast about 140 nucleotides in length, alternatively at least about 150nucleotides in length, alternatively at least about 160 nucleotides inlength, alternatively at least about 170 nucleotides in length,alternatively at least about 180 nucleotides in length, alternatively atleast about 190 nucleotides in length, alternatively at least about 200nucleotides in length, alternatively at least about 250 nucleotides inlength, alternatively at least about 300 nucleotides in length,alternatively at least about 350 nucleotides in length, alternatively atleast about 400 nucleotides in length, alternatively at least about 450nucleotides in length, alternatively at least about 500 nucleotides inlength, alternatively at least about 600 nucleotides in length,alternatively at least about 700 nucleotides in length, alternatively atleast about 800 nucleotides in length, alternatively at least about 900nucleotides in length and alternatively at least about 1000 nucleotidesin length, wherein in this context the term “about” means the referencednucleotide sequence length plus or minus 10% of that referenced length.It is noted that novel fragments of an IL-22 polypeptide-encodingnucleotide sequence may be determined in a routine manner by aligningthe IL-22 polypeptide-encoding nucleotide sequence with other knownnucleotide sequences using any of a number of well known sequencealignment programs and determining which IL-22 polypeptide-encodingnucleotide sequence fragment(s) are novel. All of such IL-22polypeptide-encoding nucleotide sequences are contemplated herein. Alsocontemplated are the IL-22 polypeptide fragments encoded by thesenucleotide molecule fragments, preferably those IL-22 polypeptidefragments that comprise a binding site for an anti-IL-22 antibody.

In another embodiment, the invention provides isolated IL-22 polypeptideencoded by any of the isolated nucleic acid sequences herein aboveidentified.

In a certain aspect, the invention concerns an isolated IL-22polypeptide, comprising an amino acid sequence having at least about 80%amino acid sequence identity, alternatively at least about 81% aminoacid sequence identity, alternatively at least about 82% amino acidsequence identity, alternatively at least about 83% amino acid sequenceidentity, alternatively at least about 84% amino acid sequence identity,alternatively at least about 85% amino acid sequence identity,alternatively at least about 86% amino acid sequence identity,alternatively at least about 87% amino acid sequence identity,alternatively at least about 88% amino acid sequence identity,alternatively at least about 89% amino acid sequence identity,alternatively at least about 90% amino acid sequence identity,alternatively at least about 91% amino acid sequence identity,alternatively at least about 92% amino acid sequence identity,alternatively at least about 93% amino acid sequence identity,alternatively at least about 94% amino acid sequence identity,alternatively at least about 95% amino acid sequence identity,alternatively at least about 96% amino acid sequence identity,alternatively at least about 97% amino acid sequence identity,alternatively at least about 98% amino acid sequence identity andalternatively at least about 99% amino acid sequence identity to (a) anIL-22 polypeptide having a full-length amino acid sequence as disclosedin FIG. 2 (SEQ ID NO: 2), (b) an amino acid sequence lacking the signalpeptide from about 1 to X, wherein X is any amino acid from about 29 toabout 38 as disclosed in FIG. 2 (SEQ ID NO: 2), or any otherspecifically defined fragment of the full-length amino acid sequence asdisclosed herein.

In a further aspect, the invention concerns an isolated IL-22polypeptide comprising an amino acid sequence having at least about 80%amino acid sequence identity, alternatively at least about 81% aminoacid sequence identity, alternatively at least about 82% amino acidsequence identity, alternatively at least about 83% amino acid sequenceidentity, alternatively at least about 84% amino acid sequence identity,alternatively at least about 85% amino acid sequence identity,alternatively at least about 86% amino acid sequence identity,alternatively at least about 87% amino acid sequence identity,alternatively at least about 88% amino acid sequence identity,alternatively at least about 89% amino acid sequence identity,alternatively at least about 90% amino acid sequence identity,alternatively at least about 91% amino acid sequence identity,alternatively at least about 92% amino acid sequence identity,alternatively at least about 93% amino acid sequence identity,alternatively at least about 94% amino acid sequence identity,alternatively at least about 95% amino acid sequence identity,alternatively at least about 96% amino acid sequence identity,alternatively at least about 97% amino acid sequence identity,alternatively at least about 98% amino acid sequence identity andalternatively at least about 99% amino acid sequence identity to anamino acid sequence encoded by the IL-22 cDNA deposited with the ATCC onDec. 7, 1999 under the ATCC deposit number PTA-1031 (DNA 125185-2806).

In a specific aspect, the invention provides an isolated IL-22polypeptide without the N-terminal signal sequence and/or the initiatingmethionine and is encoded by a nucleotide sequence that encodes such anamino acid sequence as hereinbefore described. Processes for producingthe same are also herein described, wherein those processes compriseculturing a host cell comprising a vector which comprises theappropriate encoding nucleic acid molecule under conditions suitable forexpression of the IL-22 polypeptide and recovering the IL-22 polypeptidefrom the cell culture.

In yet another embodiment, the invention concerns agonists andantagonists of a native IL-22 polypeptide as defined herein. In aparticular embodiment, the agonist or antagonist is an anti-IL-22antibody or a small molecule.

In a further embodiment, the invention concerns a method of identifyingagonists or antagonists to an IL-22 polypeptide which comprisecontacting the IL-22 polypeptide with a candidate molecule andmonitoring a biological activity mediated by said IL-22 polypeptide.Preferably, the IL-22 polypeptide is a native IL-22 polypeptide.

In a still further embodiment, the invention concerns a composition ofmatter comprising an IL-22 polypeptide, or an agonist or antagonist ofan IL-22 polypeptide as herein described, or an anti-IL-22 antibody, incombination with a carrier. Optionally, the carrier is apharmaceutically acceptable carrier.

Another embodiment of the present invention is directed to the use of anIL-22 polypeptide, or an agonist or antagonist thereof as hereinbeforedescribed, or an anti-IL-22 antibody, for the preparation of amedicament useful in the treatment of a condition which is responsive tothe IL-22 polypeptide, an agonist or antagonist thereof or an anti-IL-22antibody.

In other embodiments of the present invention, the invention providesvectors comprising DNA encoding any of the herein describedpolypeptides. Host cell comprising any such vector are also provided. Byway of example, the host cells may be CHO cells, E. coli, or yeast. Aprocess for producing any of the herein described polypeptides isfurther provided and comprises culturing host cells under conditionssuitable for expression of the desired polypeptide and recovering thedesired polypeptide from the cell culture.

In other embodiments, the invention provides chimeric moleculescomprising any of the herein described polypeptides fused to aheterologous polypeptide or amino acid sequence. Example of suchchimeric molecules comprise any of the herein described polypeptidesfused to an epitope tag sequence or a Fc region of an immunoglobulin.

In another embodiment, the invention provides an antibody which binds,preferably specifically, to any of the above or below describedpolypeptides. Optionally, the antibody is a monoclonal antibody,humanized antibody, antibody fragment or single-chain antibody.

In yet other embodiments, the invention provides oligonucleotide probeswhich may be useful for isolating genomic and cDNA nucleotide sequences,measuring or detecting expression of an associated gene or as antisenseprobes, wherein those probes may be derived from any of the above orbelow described nucleotide sequences. Preferred probe lengths aredescribed above.

In other embodiments, the invention provides for methods of detecting,diagnosing and treating pancreatic disorders by contacting biologicalsamples suspected of pancreatic disorders. Detection and diagnosis of apancreatic disorder in the biological sample may include determininglevel of IL-22 expression, effects of IL-22 expression on PAP1, orprobing the biological sample with IL-22. Treatment may includecontacting the biological sample with antagonists to IL-22, reduction ofIL-22 expression or inhibition of IL-22 binding to a receptor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a nucleotide sequence (SEQ ID NO:1) of a native sequenceIL-22 cDNA, wherein SEQ ID NO:1 is a clone designated herein as“DNA125185-2806”.

FIG. 2 shows the amino acid sequence (SEQ ID NO:2) derived from thecoding sequence of SEQ ID NO:1 shown in FIG. 1.

FIG. 3 shows Northern Blots probed with an interleukin-22 receptorprobe.

FIG. 4 shows the expression of interleukin-22 receptor RNA from varioushuman tissues as analyzed by Taqman™ analysis.

FIG. 5 shows STAT activation in a pancreatic acinar cell line stimulatedwith IL-22.

FIG. 6A shows the upregulation of Pancreatitis Associated Protein (PAP1)RNA in a pancreatic acinar cell line stimulated with IL-22 as analyzedby Northern Blot.

FIG. 6B shows the upregulation of PAP1 and Osteopontin RNA in isolatedprimary pancreatic acinar cells stimulated with IL-22 as analyzed byNorthern Blot.

FIG. 7 shows the upregulation of PAP1 in pancreas in vivo using miceinjected with IL-22 and followed by Northern Blot analysis.

FIG. 8 shows the levels of interleukin-6 (IL-6) production in wild typeand IL-10 receptor beta (IL-10Rβ) deficient mice.

FIG. 9 shows that PAP1 expression is not upregulated in pancreas in vivoin IL-10Rβ deficient mice treated with IL-22 as analyzed by NorthernBlot.

FIG. 10 shows the amino acid sequence (SEQ ID NO:3) of the IL-10Rβpolypeptide.

FIG. 11 shows the amino acid sequence (SEQ ID NO:4) of the IL-22Rpolypeptide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. Definitions

The terms “IL-22 polypeptide” and “IL-22” as used herein refers tospecific polypeptide sequences as described herein. The IL-22polypeptides described herein may be isolated from a variety of sources,such as from human tissue types or from another source, or prepared byrecombinant or synthetic methods. For example, descriptions of thepreparation of, purification of, derivation of, formation of antibodiesto or against, administration of, compositions containing, treatment ofa disease with, etc., pertain to each polypeptide of the inventionindividually. The term “IL-22 polypeptide” also includes variants of theIL-22 polypeptides disclosed herein.

A “native sequence IL-22 polypeptide” comprises a polypeptide having thesame amino acid sequence as the corresponding IL-22 polypeptide derivedfrom nature. Such native sequence IL-22 polypeptides can be isolatedfrom nature or can be produced by recombinant or synthetic means. Theterm “native sequence IL-22 polypeptide” specifically encompassesnaturally-occurring truncated or secreted forms of the specific IL-22polypeptide, naturally-occurring variant forms (e.g., alternativelyspliced forms) and naturally-occurring allelic variants of thepolypeptide. In one embodiment of the invention, the native sequenceIL-22 polypeptide comprising amino acids 1 to 179 of FIG. 2 (SEQ ID NO:2) are mature or full-length native sequence polypeptides comprising thefull-length amino acids sequences. Start and stop codons are shown inbold font and underlined in FIG. 1 (SEQ ID NO: 1). However, while theIL-22 polypeptide disclosed in FIG. 2 (SEQ ID NO: 2) is shown to beginwith methionine residues designated herein as amino acid position 1 inFIG. 2 (SEQ ID NO: 2), it is conceivable and possible that othermethionine residues located either upstream or downstream from the aminoacid position 1 in FIG. 2 (SEQ ID NO: 2) may be employed as the startingamino acid residue for the IL-22 polypeptides.

The approximate location of the “signal peptides” of the various IL-22polypeptides disclosed herein are shown in the present specificationand/or the accompanying figures. It is noted, however, that theC-terminal boundary of a signal peptide may vary, but most likely by nomore than about 5 amino acids on either side of the signal peptideC-terminal boundary as initially identified herein, wherein theC-terminal boundary of the signal peptide may be identified pursuant tocriteria routinely employed in the art for identifying that type ofamino acid sequence element (e.g., Nielsen et al., Prot. Eng. 10:1–6(1997) and von Heinje et al., Nucl. Acids. Res. 14:4683–4690 (1986)).Moreover, it is also recognized that, in some cases, cleavage of asignal sequence from a secreted polypeptide is not entirely uniform,resulting in more than one secreted species. These mature polypeptides,where the signal peptide is cleaved within no more than about 5 aminoacids on either side of the C-terminal boundary of the signal peptide asidentified herein, and the polynucleotides encoding them, arecontemplated by the present invention.

“IL-22 polypeptide variant” means an active IL-22 polypeptide as definedabove or below having at least about 80% amino acid sequence identitywith a full-length native sequence IL-22 polypeptide sequence asdisclosed herein, an IL-22 polypeptide sequence lacking the signalpeptide as disclosed herein, or any other fragment of a full-lengthIL-22 polypeptide sequence as disclosed herein. Such IL-22 polypeptidevariants include, for instance, IL-22 polypeptides wherein one or moreamino acid residues are added, or deleted, at the N- or C-terminus ofthe full-length native amino acid sequence. Ordinarily, an IL-22polypeptide variant will have at least about 80% amino acid sequenceidentity, alternatively at least about 81% amino acid sequence identity,alternatively at least about 82% amino acid sequence identity,alternatively at least about 83% amino acid sequence identity,alternatively at least about 84% amino acid sequence identity,alternatively at least about 85% amino acid sequence identity,alternatively at least about 86% amino acid sequence identity,alternatively at least about 87% amino acid sequence identity,alternatively at least about 88% amino acid sequence identity,alternatively at least about 89% amino acid sequence identity,alternatively at least about 90% amino acid sequence identity,alternatively at least about 91% amino acid sequence identity,alternatively at least about 92% amino acid sequence identity,alternatively at least about 93% amino acid sequence identity,alternatively at least about 94% amino acid sequence identity,alternatively at least about 95% amino acid sequence identity,alternatively at least about 96% amino acid sequence identity,alternatively at least about 97% amino acid sequence identity,alternatively at least about 98% amino acid sequence identity andalternatively at least about 99% amino acid sequence identity with (a)amino acids about 1 or about 33 to about 179 of the IL-22 polypeptidesequence as disclosed in FIG. 2 (SEQ ID NO: 2) (b) X to 179 of the IL-22polypeptide sequence shown in FIG. 2 (SEQ ID NO:2), wherein X is anyamino acid from 29 to 38 of FIG. 2 (SEQ ID NO: 2), or (c) any otherspecifically defined fragment of a full-length IL-22 polypeptidesequence as shown in FIG. 2 (SEQ ID NO: 2). Ordinarily, IL-22 variantpolypeptides are at least about 10 amino acids in length, alternativelyat least about 20 amino acids in length, alternatively at least about 30amino acids in length, alternatively at least about 40 amino acids inlength, alternatively at least about 50 amino acids in length,alternatively at least about 60 amino acids in length, alternatively atleast about 70 amino acids in length, alternatively at least about 80amino acids in length, alternatively at least about 90 amino acids inlength, alternatively at least about 100 amino acids in length,alternatively at least about 150 amino acids in length, alternatively atleast about 200 amino acids in length, alternatively at least about 300amino acids in length, or more.

“Percent (%) amino acid sequence identity” with respect to the IL-22polypeptide sequences identified herein is defined as the percentage ofamino acid residues in a candidate sequence that are identical with theamino acid residues in the specific IL-22 polypeptide sequence, afteraligning the sequences and introducing gaps, if necessary, to achievethe maximum percent sequence identity, and not considering anyconservative substitutions as part of the sequence identity. Alignmentfor purposes of determining percent amino acid sequence identity can beachieved in various ways that are within the skill in the art, forinstance, using publicly available computer software such as BLAST,BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the artcan determine appropriate parameters for measuring alignment, includingany algorithms needed to achieve maximal alignment over the full lengthof the sequences being compared. For purposes herein, however, % aminoacid sequence identity values are generated using the sequencecomparison computer program ALIGN-2, wherein the complete source codefor the ALIGN-2 program is provided in Table 1 below. The ALIGN-2sequence comparison computer program was authored by Genentech, Inc. andthe source code shown in Table 1 below has been filed with userdocumentation in the U.S. Copyright Office, Washington D.C., 20559,where it is registered under U.S. Copyright Registration No. TXU510087.The ALIGN-2 program is publicly available through Genentech, Inc., SouthSan Francisco, Calif. or may be compiled from the source code providedin Table 1 below. The ALIGN-2 program should be compiled for use on aUNIX operating system, preferably digital UNIX V4.0D. All sequencecomparison parameters are set by the ALIGN-2 program and do not vary.

In situations where ALIGN-2 is employed for amino acid sequencecomparisons, the % amino acid sequence identity of a given amino acidsequence A to, with, or against a given amino acid sequence B (which canalternatively be phrased as a given amino acid sequence A that has orcomprises a certain % amino acid sequence identity to, with, or againsta given amino acid sequence B) is calculated as follows:100 times the fraction X/Ywhere X is the number of amino acid residues scored as identical matchesby the sequence alignment program ALIGN-2 in that program's alignment ofA and B, and where Y is the total number of amino acid residues in B. Itwill be appreciated that where the length of amino acid sequence A isnot equal to the length of amino acid sequence B, the % amino acidsequence identity of A to B will not equal the % amino acid sequenceidentity of B to A. As examples of % amino acid sequence identitycalculations using this method, Tables 2 and 3 demonstrate how tocalculate the % amino acid sequence identity of the amino acid sequencedesignated “Comparison Protein” to the amino acid sequence designated“IL-22”, wherein “IL-22” represents the amino acid sequence of ahypothetical IL-22 polypeptide of interest, “Comparison Protein”represents the amino acid sequence of a polypeptide against which the“IL-22” polypeptide of interest is being compared, and “X, “Y” and “Z”each represent different hypothetical amino acid residues.

Unless specifically stated otherwise, all % amino acid sequence identityvalues used herein are obtained as described in the immediatelypreceding paragraph using the ALIGN-2 computer program. However, % aminoacid sequence identity values may also be obtained as described below byusing the WU-BLAST-2 computer program (Altschul et al., Methods inEnzymology 266:460–480 (1996)). Most of the WU-BLAST-2 search parametersare set to the default values. Those not set to default values, i.e.,the adjustable parameters, are set with the following values: overlapspan=1, overlap fraction=0.125, word threshold (T)=11, and scoringmatrix=BLOSUM62. When WU-BLAST-2 is employed, a % amino acid sequenceidentity value is determined by dividing (a) the number of matchingidentical amino acid residues between the amino acid sequence of theIL-22 polypeptide of interest having a sequence derived from the nativeIL-22 polypeptide and the comparison amino acid sequence of interest(i.e., the sequence against which the IL-22 polypeptide of interest isbeing compared which may be an IL-22 variant polypeptide) as determinedby WU-BLAST-2 by (b) the total number of amino acid residues of theIL-22 polypeptide of interest. For example, in the statement “apolypeptide comprising an the amino acid sequence A which has or havingat least 80% amino acid sequence identity to the amino acid sequence B”,the amino acid sequence A is the comparison amino acid sequence ofinterest and the amino acid sequence B is the amino acid sequence of theIL-22 polypeptide of interest.

Percent amino acid sequence identity may also be determined using thesequence comparison program NCBI-BLAST2 (Altschul et al., Nucleic AcidsRes. 25:3389–3402 (1997)). The NCBI-BLAST2 sequence comparison programmay be downloaded from http://www.ncbi.nlm.nih.govor otherwise obtainedfrom the National Institute of Health, Bethesda, Md. NCBI-BLAST2 usesseveral search parameters, wherein all of those search parameters areset to default values including, for example, unmask=yes, strand=all,expected occurrences=10, minimum low complexity length=15/5, multi-passe-value=0.01, constant for multi-pass=25, dropoff for final gappedalignment=25 and scoring matrix=BLOSUM62.

In situations where NCBI-BLAST2 is employed for amino acid sequencecomparisons, the % amino acid sequence identity of a given amino acidsequence A to, with, or against a given amino acid sequence B (which canalternatively be phrased as a given amino acid sequence A that has orcomprises a certain % amino acid sequence identity to, with, or againsta given amino acid sequence B) is calculated as follows:100 times the fraction X/Ywhere X is the number of amino acid residues scored as identical matchesby the sequence alignment program NCBI-BLAST2 in that program'salignment of A and B, and where Y is the total number of amino acidresidues in B. It will be appreciated that where the length of aminoacid sequence A is not equal to the length of amino acid sequence B, the% amino acid sequence identity of A to B will not equal the % amino acidsequence identity of B to A.

“IL-22 variant polynucleotide” or “IL-22 variant nucleic acid sequence”means a nucleic acid molecule which encodes an active IL-22 polypeptideas defined below and which has at least about 80% nucleic acid sequenceidentity with a nucleotide acid sequence encoding a full-length nativesequence IL-22 polypeptide sequence as disclosed herein, a full-lengthnative sequence IL-22 polypeptide sequence lacking the signal peptide asdisclosed herein, or any other fragment of a full-length IL-22polypeptide sequence as disclosed herein. Ordinarily, an IL-22 variantpolynucleotide will have at least about 80% nucleic acid sequenceidentity, alternatively at least about 81% nucleic acid sequenceidentity, alternatively at least about 82% nucleic acid sequenceidentity, alternatively at least about 83% nucleic acid sequenceidentity, alternatively at least about 84% nucleic acid sequenceidentity, alternatively at least about 85% nucleic acid sequenceidentity, alternatively at least about 86% nucleic acid sequenceidentity, alternatively at least about 87% nucleic acid sequenceidentity, alternatively at least about 88% nucleic acid sequenceidentity, alternatively at least about 89% nucleic acid sequenceidentity, alternatively at least about 90% nucleic acid sequenceidentity, alternatively at least about 91% nucleic acid sequenceidentity, alternatively at least about 92% nucleic acid sequenceidentity, alternatively at least about 93% nucleic acid sequenceidentity, alternatively at least about 94% nucleic acid sequenceidentity, alternatively at least about 95% nucleic acid sequenceidentity, alternatively at least about 96% nucleic acid sequenceidentity, alternatively at least about 97% nucleic acid sequenceidentity, alternatively at least about 98% nucleic acid sequenceidentity and alternatively at least about 99% nucleic acid sequenceidentity with a nucleic acid sequence encoding a full-length nativesequence IL-22 polypeptide sequence as disclosed herein, a full-lengthnative sequence IL-22 polypeptide sequence lacking the signal peptide asdisclosed herein, an extra cellular domain of an IL-22 polypeptide, withor without the signal sequence, as disclosed herein or any otherfragment of a full-length IL-22 polypeptide sequence as disclosedherein. Variants do not encompass the native nucleotide sequence.

Ordinarily, IL-22 variant polynucleotides are at least about 30nucleotides in length, alternatively at least about 60 nucleotides inlength, alternatively at least about 90 nucleotides in length,alternatively at least about 120 nucleotides in length, alternatively atleast about 150 nucleotides in length, alternatively at least about 180nucleotides in length, alternatively at least about 210 nucleotides inlength, alternatively at least about 240 nucleotides in length,alternatively at least about 270 nucleotides in length, alternatively atleast about 300 nucleotides in length, alternatively at least about 450nucleotides in length, alternatively at least about 600 nucleotides inlength, alternatively at least about 900 nucleotides in length, or more.

“Percent (%) nucleic acid sequence identity” with respect toIL-22-encoding nucleic acid sequences identified herein is defined asthe percentage of nucleotides in a candidate sequence that are identicalwith the nucleotides in the IL-22 nucleic acid sequence of interest,after aligning the sequences and introducing gaps, if necessary, toachieve the maximum percent sequence identity. Alignment for purposes ofdetermining percent nucleic acid sequence identity can be achieved invarious ways that are within the skill in the art, for instance, usingpublicly available computer software such as BLAST, BLAST-2, ALIGN orMegalign (DNASTAR) software. For purposes herein, however, % nucleicacid sequence identity values are generated using the sequencecomparison computer program ALIGN-2, wherein the complete source codefor the ALIGN-2 program is provided in Table 1 below. The ALIGN-2sequence comparison computer program was authored by Genentech, Inc. andthe source code shown in Table 1 below has been filed with userdocumentation in the U.S. Copyright Office, Washington D.C., 20559,where it is registered under U.S. Copyright Registration No. TXU510087.The ALIGN-2 program is publicly available through Genentech, Inc., SouthSan Francisco, Calif. or may be compiled from the source code providedin Table 1 below. The ALIGN-2 program should be compiled for use on aUNIX operating system, preferably digital UNIX V4.0D. All sequencecomparison parameters are set by the ALIGN-2 program and do not vary.

In situations where ALIGN-2 is employed for nucleic acid sequencecomparisons, the % nucleic acid sequence identity of a given nucleicacid sequence C to, with, or against a given nucleic acid sequence D(which can alternatively be phrased as a given nucleic acid sequence Cthat has or comprises a certain % nucleic acid sequence identity to,with, or against a given nucleic acid sequence D) is calculated asfollows:100 times the fraction W/Zwhere W is the number of nucleotides scored as identical matches by thesequence alignment program ALIGN-2 in that program's alignment of C andD, and where Z is the total number of nucleotides in D. It will beappreciated that where the length of nucleic acid sequence C is notequal to the length of nucleic acid sequence D, the % nucleic acidsequence identity of C to D will not equal the % nucleic acid sequenceidentity of D to C. As examples of % nucleic acid sequence identitycalculations, Tables 4 and 5, demonstrate how to calculate the % nucleicacid sequence identity of the nucleic acid sequence designated“Comparison DNA” to the nucleic acid sequence designated “IL-22-DNA”,wherein “IL-22-DNA” represents a hypothetical IL-22-encoding nucleicacid sequence of interest, “Comparison DNA” represents the nucleotidesequence of a nucleic acid molecule against which the “IL-22-DNA”nucleic acid molecule of interest is being compared, and “N”, “L” and“V” each represent different hypothetical nucleotides.

Unless specifically stated otherwise, all % nucleic acid sequenceidentity values used herein are obtained as described in the immediatelypreceding paragraph using the ALIGN-2 computer program. However, %nucleic acid sequence identity values may also be obtained as describedbelow by using the WU-BLAST-2 computer program (Altschul et al., Methodsin Enzymology 266:460–480 (1996)). Most of the WU-BLAST-2 searchparameters are set to the default values. Those not set to defaultvalues, i.e., the adjustable parameters, are set with the followingvalues: overlap span=1, overlap fraction=0.125, word threshold (T)=11,and scoring matrix=BLOSUM62. When WU-BLAST-2 is employed, a % nucleicacid sequence identity value is determined by dividing (a) the number ofmatching identical nucleotides between the nucleic acid sequence of theIL-22 polypeptide-encoding nucleic acid molecule of interest having asequence derived from the native sequence IL-22 polypeptide-encodingnucleic acid and the comparison nucleic acid molecule of interest (i.e.,the sequence against which the IL-22 polypeptide-encoding nucleic acidmolecule of interest is being compared which may be a variant IL-22polynucleotide) as determined by WU-BLAST-2 by (b) the total number ofnucleotides of the IL-22 polypeptide-encoding nucleic acid molecule ofinterest. For example, in the statement “an isolated nucleic acidmolecule comprising a nucleic acid sequence A which has or having atleast 80% nucleic acid sequence identity to the nucleic acid sequenceB”, the nucleic acid sequence A is the comparison nucleic acid moleculeof interest and the nucleic acid sequence B is the nucleic acid sequenceof the IL-22 polypeptide-encoding nucleic acid molecule of interest.

Percent nucleic acid sequence identity may also be determined using thesequence comparison program NCBI-BLAST2 (Altschul et al., Nucleic AcidsRes. 25:3389–3402 (1997)). The NCBI-BLAST2 sequence comparison programmay be downloaded from http://www.ncbi.nlm.nih.gov or otherwise obtainedfrom the National Institute of Health, Bethesda, Md. NCBI-BLAST2 usesseveral search parameters, wherein all of those search parameters areset to default values including, for example, unmask=yes, strand=all,expected occurrences=10, minimum low complexity length=15/5, multi-passe-value=0.01, constant for multi-pass=25, dropoff for final gappedalignment=25 and scoring matrix=BLOSUM62.

In situations where NCBI-BLAST2 is employed for sequence comparisons,the % nucleic acid sequence identity of a given nucleic acid sequence Cto, with, or against a given nucleic acid sequence D (which canalternatively be phrased as a given nucleic acid sequence C that has orcomprises a certain % nucleic acid sequence identity to, with, oragainst a given nucleic acid sequence D) is calculated as follows:100 times the fraction W/Zwhere W is the number of nucleotides scored as identical matches by thesequence alignment program NCBI-BLAST2 in that program's alignment of Cand D, and where Z is the total number of nucleotides in D. It will beappreciated that where the length of nucleic acid sequence C is notequal to the length of nucleic acid sequence D, the % nucleic acidsequence identity of C to D will not equal the % nucleic acid sequenceidentity of D to C.

In other embodiments, IL-22 variant polynucleotides are nucleic acidmolecules that encode an active IL-22 polypeptide and which are capableof hybridizing, preferably under stringent hybridization and washconditions, to nucleotide sequences encoding a full-length IL-22polypeptide as disclosed herein. IL-22 variant polypeptides may be thosethat are encoded by an IL-22 variant polynucleotide.

“Isolated,” when used to describe the various polypeptides disclosedherein, means polypeptide that has been identified and separated and/orrecovered from a component of its natural environment. Contaminantcomponents of its natural environment are materials that would typicallyinterfere with diagnostic or therapeutic uses for the polypeptide, andmay include enzymes, hormones, and other proteinaceous ornon-proteinaceous solutes. In preferred embodiments, the polypeptidewill be purified (1) to a degree sufficient to obtain at least 15residues of N-terminal or internal amino acid sequence by use of aspinning cup sequenator, or (2) to homogeneity by SDS-PAGE undernon-reducing or reducing conditions using Coomassie blue or, preferably,silver stain. Isolated polypeptide includes polypeptide in situ withinrecombinant cells, since at least one component of the IL-22 polypeptidenatural environment will not be present. Ordinarily, however, isolatedpolypeptide will be prepared by at least one purification step.

An “isolated” IL-22 polypeptide-encoding nucleic acid or otherpolypeptide-encoding nucleic acid is a nucleic acid molecule that isidentified and separated from at least one contaminant nucleic acidmolecule with which it is ordinarily associated in the natural source ofthe polypeptide-encoding nucleic acid. An isolated polypeptide-encodingnucleic acid molecule is other than in the form or setting in which itis found in nature. Isolated polypeptide-encoding nucleic acid moleculestherefore are distinguished from the specific polypeptide-encodingnucleic acid molecule as it exists in natural cells. However, anisolated polypeptide-encoding nucleic acid molecule includespolypeptide-encoding nucleic acid molecules contained in cells thatordinarily express the polypeptide where, for example, the nucleic acidmolecule is in a chromosomal location different from that of naturalcells.

The term “control sequences” refers to DNA sequences necessary for theexpression of an operably linked coding sequence in a particular hostorganism. The control sequences that are suitable for prokaryotes, forexample, include a promoter, optionally an operator sequence, and aribosome binding site. Eukaryotic cells are known to utilize promoters,polyadenylation signals, and enhancers.

Nucleic acid is “operably linked” when it is placed into a functionalrelationship with another nucleic acid sequence. For example, DNA for apresequence or secretory leader is operably linked to DNA for apolypeptide if it is expressed as a preprotein that participates in thesecretion of the polypeptide; a promoter or enhancer is operably linkedto a coding sequence if it affects the transcription of the sequence; ora ribosome binding site is operably linked to a coding sequence if it ispositioned so as to facilitate translation. Generally, “operably linked”means that the DNA sequences being linked are contiguous, and, in thecase of a secretory leader, contiguous and in reading phase. However,enhancers do not have to be contiguous. Linking is accomplished byligation at convenient restriction sites. If such sites do not exist,the synthetic oligonucleotide adaptors or linkers are used in accordancewith conventional practice.

The term “antibody” is used in the broadest sense and specificallycovers, for example, single anti-IL-22 monoclonal antibodies (includingagonist, antagonist, and neutralizing antibodies), anti-IL-22 antibodycompositions with polyepitopic specificity, single chain anti-IL-22antibodies, and fragments of anti-IL-22 antibodies (see below). The term“monoclonal antibody” as used herein refers to an antibody obtained froma population of substantially homogeneous antibodies, i.e., theindividual antibodies comprising the population are identical except forpossible naturally-occurring mutations that may be present in minoramounts.

“Stringency” of hybridization reactions is readily determinable by oneof ordinary skill in the art, and generally is an empirical calculationdependent upon probe length, washing temperature, and saltconcentration. In general, longer probes require higher temperatures forproper annealing, while shorter probes need lower temperatures.Hybridization generally depends on the ability of denatured DNA toreanneal when complementary strands are present in an environment belowtheir melting temperature. The higher the degree of desired homologybetween the probe and hybridizable sequence, the higher the relativetemperature which can be used. As a result, it follows that higherrelative temperatures would tend to make the reaction conditions morestringent, while lower temperatures less so. For additional details andexplanation of stringency of hybridization reactions, see Ausubel etal., Current Protocols in Molecular Biology, Wiley IntersciencePublishers, (1995).

“Stringent conditions” or “high stringency conditions”, as definedherein, may be identified by those that: (1) employ low ionic strengthand high temperature for washing, for example 0.015 M sodiumchloride/0.0015 M sodium citrate/0.1% sodium dodecyl sulfate at 50° C.;(2) employ during hybridization a denaturing agent, such as formamide,for example, 50% (v/v) formamide with 0.1% bovine serum albumin/0.1%Ficoll/0.1% polyvinylpyrrolidone/50 mM sodium phosphate buffer at pH 6.5with 750 mM sodium chloride, 75 mM sodium citrate at 42° C.; or (3)employ 50% formamide, 5×SSC (0.75 M NaCl, 0.075 M sodium citrate), 50 mMsodium phosphate (pH 6.8), 0.1% sodium pyrophosphate, 5× Denhardt'ssolution, sonicated salmon sperm DNA (50 μg/ml), 0.1% SDS, and 10%dextran sulfate at 42° C., with washes at 42° C. in 0.2×SSC (sodiumchloride/sodium citrate) and 50% formamide at 55° C., followed by ahigh-stringency wash consisting of 0.1×SSC containing EDTA at 55° C.

“Moderately stringent conditions” may be identified as described bySambrook et al., Molecular Cloning: A Laboratory Manual, New York: ColdSpring Harbor Press, 1989, and include the use of washing solution andhybridization conditions (e.g., temperature, ionic strength and % SDS)less stringent that those described above. An example of moderatelystringent conditions is overnight incubation at 37° C. in a solutioncomprising: 20% formamide, 5×SSC (150 mM NaCl, 15 mM trisodium citrate),50 mM sodium phosphate (pH 7.6),5× Denhardt's solution, 10% dextransulfate, and 20 mg/ml denatured sheared salmon sperm DNA, followed bywashing the filters in 1×SSC at about 37–50° C. The skilled artisan willrecognize how to adjust the temperature, ionic strength, etc. asnecessary to accommodate factors such as probe length and the like.

The term “epitope tagged” when used herein refers to a chimericpolypeptide comprising an IL-22 polypeptide fused to a “tagpolypeptide”. The tag polypeptide has enough residues to provide anepitope against which an antibody can be made, yet is short enough suchthat it does not interfere with activity of the polypeptide to which itis fused. The tag polypeptide preferably also is fairly unique so thatthe antibody does not substantially cross-react with other epitopes.Suitable tag polypeptides generally have at least six amino acidresidues and usually between about 8 and 50 amino acid residues(preferably, between about 10 and 20 amino acid residues).

As used herein, the term “immunoadhesin” designates antibody-likemolecules which combine the binding specificity of a heterologousprotein (an “adhesin”) with the effector functions of immunoglobulinconstant domains. Structurally, the immunoadhesins comprise a fusion ofan amino acid sequence with the desired binding specificity which isother than the antigen recognition and binding site of an antibody(i.e., is “heterologous”), and an immunoglobulin constant domainsequence. The adhesin part of an immunoadhesin molecule typically is acontiguous amino acid sequence comprising at least the binding site of areceptor or a ligand. The immunoglobulin constant domain sequence in theimmunoadhesin may be obtained from any immunoglobulin, such as IgG-1,IgG-2, IgG-3, or IgG-4 subtypes, IgA (including IgA-1 and IgA-2), IgE,IgD or IgM.

“Active” or “activity” for the purposes herein refers to form(s) of anIL-22 polypeptide which retain a biological and/or an immunologicalactivity of native or naturally-occurring IL-22, wherein “biological”activity refers to a biological function (either inhibitory orstimulatory) caused by a native or naturally-occurring IL-22 other thanthe ability to induce the production of an antibody against an antigenicepitope possessed by a native or naturally-occurring IL-22 and an“immunological” activity refers to the ability to induce the productionof an antibody against an antigenic epitope possessed by a native ornaturally-occurring IL-22. A preferred biological activity is inductionof PAP1 expression. PAP1 is a secreted protein related to the REG familyof trophic factors and was initially characterized as a protein withelevated expression in pancreatitis (Iovanna et al., (1991) J. Biol.Chem., 266, 24664–24669). In vivo injection of IL-22 resulted in rapidinduction of PAP1 expression in pancreas.

The term “antagonist” is used in the broadest sense, and includes anymolecule that partially or fully blocks, inhibits, or neutralizes abiological activity of a native IL-22 polypeptide disclosed herein. In asimilar manner, the term “agonist” is used in the broadest sense andincludes any molecule that mimics a biological activity of a nativeIL-22 polypeptide disclosed herein. Suitable agonist or antagonistmolecules specifically include agonist or antagonist antibodies orantibody fragments, fragments or amino acid sequence variants of nativeIL-22 polypeptides, peptides, antisense oligonucleotides, small organicmolecules, etc. Methods for identifying agonists or antagonists of anIL-22 polypeptide may comprise contacting an IL-22 polypeptide with acandidate agonist or antagonist molecule and measuring a detectablechange in one or more biological activities normally associated with theIL-22 polypeptide.

“Treatment” refers to both therapeutic treatment and prophylactic orpreventative measures, wherein the object is to prevent or slow down(lessen) the targeted pathologic condition or disorder. Those in need oftreatment include those already with the disorder as well as those proneto have the disorder or those in whom the disorder is to be prevented.

“Chronic” administration refers to administration of the agent(s) in acontinuous mode as opposed to an acute mode, so as to maintain theinitial therapeutic effect (activity) for an extended period of time.“Intermittent” administration is treatment that is not consecutivelydone without interruption, but rather is cyclic in nature.

“Mammal” for purposes of treatment refers to any animal classified as amammal, including humans, domestic and farm animals, and zoo, sports, orpet animals, such as dogs, cats, cattle, horses, sheep, pigs, goats,rabbits, etc. Preferably, the mammal is human.

Administration “in combination with” one or more further therapeuticagents includes simultaneous (concurrent) and consecutive administrationin any order.

“Carriers” as used herein include pharmaceutically acceptable carriers,excipients, or stabilizers which are nontoxic to the cell or mammalbeing exposed thereto at the dosages and concentrations employed. Oftenthe physiologically acceptable carrier is an aqueous pH bufferedsolution. Examples of physiologically acceptable carriers includebuffers such as phosphate, citrate, and other organic acids;antioxidants including ascorbic acid; low molecular weight (less thanabout 10 residues) polypeptide; proteins, such as serum albumin,gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, arginine or lysine; monosaccharides, disaccharides, andother carbohydrates including glucose, mannose, or dextrins; chelatingagents such as EDTA; sugar alcohols such as mannitol or sorbitol;salt-forming counterions such as sodium; and/or nonionic surfactantssuch as TWEEN™, polyethylene glycol (PEG), and PLURONICS™.

“Antibody fragments” comprise a portion of an intact antibody,preferably the antigen binding or variable region of the intactantibody. Examples of antibody fragments include Fab, Fab′, F(ab′)₂, andFv fragments; diabodies; linear antibodies (Zapata et al., Protein Eng.8(10): 1057–1062[1995]); single-chain antibody molecules; andmultispecific antibodies formed from antibody fragments.

Papain digestion of antibodies produces two identical antigen-bindingfragments, called “Fab” fragments, each with a single antigen-bindingsite, and a residual “Fc” fragment, a designation reflecting the abilityto crystallize readily. Pepsin treatment yields an F(ab′)₂ fragment thathas two antigen-combining sites and is still capable of cross-linkingantigen.

“Fv” is the minimum antibody fragment which contains a completeantigen-recognition and -binding site. This region consists of a dimerof one heavy- and one light-chain variable domain in tight, non-covalentassociation. It is in this configuration that the three CDRs of eachvariable domain interact to define an antigen-binding site on thesurface of the V_(H)–V_(L) dimer. Collectively, the six CDRs conferantigen-binding specificity to the antibody. However, even a singlevariable domain (or half of an Fv comprising only three CDRs specificfor an antigen) has the ability to recognize and bind antigen, althoughat a lower affinity than the entire binding site.

The Fab fragment also contains the constant domain of the light chainand the first constant domain (CH1) of the heavy chain. Fab fragmentsdiffer from Fab′ fragments by the addition of a few residues at thecarboxy terminus of the heavy chain CH1 domain including one or morecysteines from the antibody hinge region. Fab′-SH is the designationherein for Fab′ in which the cysteine residue(s) of the constant domainsbear a free thiol group. F(ab′)₂ antibody fragments originally wereproduced as pairs of Fab′ fragments which have hinge cysteines betweenthem. Other chemical couplings of antibody fragments are also known.

The “light chains” of antibodies (immunoglobulins) from any vertebratespecies can be assigned to one of two clearly distinct types, calledkappa and lambda, based on the amino acid sequences of their constantdomains.

Depending on the amino acid sequence of the constant domain of theirheavy chains, immunoglobulins can be assigned to different classes.There are five major classes of immunoglobul ins: IgA, IgD, IgE, IgG,and IgM, and several of these may be further divided into subclasses(isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgA, and IgA2.

“Single-chain Fv” or “sFv” antibody fragments comprise the V_(H) andV_(L) domains of antibody, wherein these domains are present in a singlepolypeptide chain. Preferably, the Fv polypeptide further comprises apolypeptide linker between the V_(H) and V_(L) domains which enables thesFv to form the desired structure for antigen binding. For a review ofsFv, see Pluckthun in The Pharmacology of Monoclonal Antibodies, vol.113, Rosenburg and Moore eds., Springer-Verlag, New York, pp. 269–315(1994).

The term “diabodies” refers to small antibody fragments with twoantigen-binding sites, which fragments comprise a heavy-chain variabledomain (V_(H)) connected to a light-chain variable domain (V_(L)) in thesame polypeptide chain (V_(H)–V_(L)). By using a linker that is tooshort to allow pairing between the two domains on the same chain, thedomains are forced to pair with the complementary domains of anotherchain and create two antigen-binding sites. Diabodies are described morefully in, for example, EP 404,097; WO 93/11161; and Hollinger et al.,Proc. Natl. Acad. Sci. USA, 90:6444–6448 (1993).

An “isolated” antibody is one which has been identified and separatedand/or recovered from a component of its natural environment.Contaminant components of its natural environment are materials whichwould interfere with diagnostic or therapeutic uses for the antibody,and may include enzymes, hormones, and other proteinaceous ornonproteinaceous solutes. In preferred embodiments, the antibody will bepurified (1) to greater than 95% by weight of antibody as determined bythe Lowry method, and most preferably more than 99% by weight, (2) to adegree sufficient to obtain at least 15 residues of N-terminal orinternal amino acid sequence by use of a spinning cup sequenator, or (3)to homogeneity by SDS-PAGE under reducing or nonreducing conditionsusing Coomassie blue or, preferably, silver stain. Isolated antibodyincludes the antibody in situ within recombinant cells since at leastone component of the antibody's natural environment will not be present.Ordinarily, however, isolated antibody will be prepared by at least onepurification step.

An antibody that “specifically binds to” or is “specific for” aparticular polypeptide or an epitope on a particular polypeptide is onethat binds to that particular polypeptide or epitope on a particularpolypeptide without substantially binding to any other polypeptide orpolypeptide epitope.

The word “label” when used herein refers to a detectable compound orcomposition which is conjugated directly or indirectly to the antibodyso as to generate a “labeled” antibody. The label may be detectable byitself (e.g. radioisotope labels or fluorescent labels) or, in the caseof an enzymatic label, may catalyze chemical alteration of a substratecompound or composition which is detectable.

By “solid phase” is meant a non-aqueous matrix to which the antibody ofthe present invention can adhere. Examples of solid phases encompassedherein include those formed partially or entirely of glass (e.g.,controlled pore glass), polysaccharides (e.g., agarose),polyacrylamides, polystyrene, polyvinyl alcohol and silicones. Incertain embodiments, depending on the context, the solid phase cancomprise the well of an assay plate; in others it is a purificationcolumn (e.g., an affinity chromatography column). This term alsoincludes a discontinuous solid phase of discrete particles, such asthose described in U.S. Pat. No. 4,275,149.

A “liposome” is a small vesicle composed of various types of lipids,phospholipids and/or surfactant which is useful for delivery of a drug(such as an IL-22 polypeptide or antibody thereto) to a mammal. Thecomponents of the liposome are commonly arranged in a bilayer formation,similar to the lipid arrangement of biological membranes.

A “small molecule” is defined herein to have a molecular weight belowabout 500 Daltons.

An “effective amount” of a polypeptide disclosed herein or an agonist orantagonist thereof is an amount sufficient to carry out a specificallystated purpose. An “effective amount” may be determined empirically andin a routine manner, in relation to the stated purpose.

An “activated pancreas” as defined herein is when the digestive enzymesof the pancreas are activated and begin to attack pancreatic tissue.

A “bioactive molecule” is defined herein as a toxin, a radiolabel or anantibody.

TABLE 2 IL-22 XXXXXXXXXXXXXXX (Length = 15 amino acids) ComparisonXXXXXYYYYYYY (Length = 12 amino acids) Protein % amino acid sequenceidentity = (the number of identically matching amino acid residuesbetween the two polypeptide sequences as determined by ALIGN-2) dividedby (the total number of amino acid residues of the IL-22 polypeptide) =5 divided by 15 = 33.3%

TABLE 3 IL-22 XXXXXXXXXX (Length = 10 amino acids) ComparisonXXXXXYYYYYYZZYZ (Length = 15 amino acids) Protein % amino acid sequenceidentity = (the number of identically matching amino acid residuesbetween the two polypeptide sequences as determined by ALIGN-2) dividedby (the total number of amino acid residues of the IL-22 polypeptide) =5 divided by 10 = 50%

TABLE 4 IL-22-DNA NNNNNNNNNNNNNN (Length = 14 nucleotides) ComparisonNNNNNNLLLLLLLLLL (Length = 16 nucleotides) DNA % nucleic acid sequenceidentity = (the number of identically matching nucleotides between thetwo nucleic acid sequences as determined by ALIGN-2) divided by (thetotal number of nucleotides of the IL-22-DNA nucleic acid sequence) = 6divided by 14 = 42.9%

TABLE 5 IL-22-DNA NNNNNNNNNNNN (Length = 12 nucleotides) Comparison DNANNNNLLLVV (Length = 9 nucleotides) % nucleic acid sequence identity =(the number of identically matching nucleotides between the two nucleicacid sequences as determined by ALIGN-2) divided by (the total number ofnucleotides of the IL-22-DNA nucleic acid sequence) = 4 divided by 12 =33.3%II. Compositions and Methods of the Invention

A. Full-Length IL-22 Polypeptides

The present invention provides newly identified and isolated nucleotidesequences encoding polypeptides referred to in the present applicationas IL-22 polypeptides. In particular, cDNAs encoding various IL-22polypeptides have been identified and isolated, as disclosed in furtherdetail in the Examples below. It is noted that proteins produced inseparate expression rounds may be given different IL-22 numbers but theUNQ number is unique for any given DNA and the encoded protein, and willnot be changed. However, for sake of simplicity, in the presentspecification the protein encoded by the full length native nucleic acidmolecules disclosed herein as well as all further native homologues andvariants included in the foregoing definition of IL-22, will be referredto as “IL-22”, regardless of their origin or mode of preparation.

As disclosed in the Examples below, various cDNA clones have beendeposited with the ATCC. The actual nucleotide sequences of those clonescan readily be determined by the skilled artisan by sequencing of thedeposited clone using routine methods in the art. The predicted aminoacid sequence can be determined from the nucleotide sequence usingroutine skill. For the IL-22 polypeptides and encoding nucleic acidsdescribed herein, Applicants have identified what is believed to be thereading frame best identifiable with the sequence information availableat the time.

B. IL-22 Polypeptide Variants

In addition to the full-length native sequence IL-22 polypeptidesdescribed herein, it is contemplated that IL-22 variants can beprepared. IL-22 variants can be prepared by introducing appropriatenucleotide changes into the IL-22 DNA, and/or by synthesis of thedesired IL-22 polypeptide. Those skilled in the art will appreciate thatamino acid changes may alter post-translational processes of the IL-22,such as changing the number or position of glycosylation sites oraltering the membrane anchoring characteristics.

Variations in the native full-length sequence IL-22 or in variousdomains of the IL-22 described herein, can be made, for example, usingany of the techniques and guidelines for conservative andnon-conservative mutations set forth, for instance, in U.S. Pat. No.5,364,934. Variations may be a substitution, deletion or insertion ofone or more codons encoding the IL-22 that results in a change in theamino acid sequence of the IL-22 as compared with the native sequenceIL-22. Optionally the variation is by substitution of at least one aminoacid with any other amino acid in one or more of the domains of theIL-22. Guidance in determining which amino acid residue may be inserted,substituted or deleted without adversely affecting the desired activitymay be found by comparing the sequence of the IL-22 with that ofhomologous known protein molecules and minimizing the number of aminoacid sequence changes made in regions of high homology. Amino acidsubstitutions can be the result of replacing one amino acid with anotheramino acid having similar structural and/or chemical properties, such asthe replacement of a leucine with a serine, i.e., conservative aminoacid replacements. Insertions or deletions may optionally be in therange of about 1 to 5 amino acids. The variation allowed may bedetermined by systematically making insertions, deletions orsubstitutions of amino acids in the sequence and testing the resultingvariants for activity exhibited by the full-length or mature nativesequence.

IL-22 polypeptide fragments are provided herein. Such fragments may betruncated at the N-terminus or C-terminus, or may lack internalresidues, for example, when compared with a full length native protein.Certain fragments lack amino acid residues that are not essential for adesired biological activity of the IL-22 polypeptide.

IL-22 fragments may be prepared by any of a number of conventionaltechniques. Desired peptide fragments may be chemically synthesized. Analternative approach involves generating IL-22 fragments by enzymaticdigestion, e.g., by treating the protein with an enzyme known to cleaveproteins at sites defined by particular amino acid residues, or bydigesting the DNA with suitable restriction enzymes and isolating thedesired fragment. Yet another suitable technique involves isolating andamplifying a DNA fragment encoding a desired polypeptide fragment, bypolymerase chain reaction (PCR). Oligonucleotides that define thedesired termini of the DNA fragment are employed at the 5′ and 3′primers in the PCR. Preferably, IL-22 polypeptide fragments share atleast one biological and/or immunological activity with the native IL-22polypeptide disclosed herein.

In particular embodiments, conservative substitutions of interest areshown in Table 6 under the heading of preferred substitutions. If suchsubstitutions result in a change in biological activity, then moresubstantial changes, denominated exemplary substitutions in Table 6, oras further described below in reference to amino acid classes, areintroduced and the products screened.

TABLE 6 Original Exemplary Preferred Residue Substitutions SubstitutionsAla (A) val; leu; ile val Arg (R) lys; gln; asn lys Asn (N) gln; his;lys; arg gln Asp (D) glu glu Cys (C) ser ser Gln (Q) asn asn Glu (E) aspasp Gly (G) pro; ala ala His (H) asn; gln; lys; arg arg Ile (I) leu;val; met; ala; phe; leu norleucine Leu (L) norleucine; ile; val; ilemet; ala; phe Lys (K) arg; gln; asn arg Met (M) leu; phe; ile leu Phe(F) leu; val; ile; ala; tyr leu Pro (P) ala ala Ser (S) thr thr Thr (T)ser ser Trp (W) tyr; phe tyr Tyr (Y) trp; phe; thr; ser phe Val (V) ile;leu; met; phe; leu ala; norleucine

Substantial modifications in function or immunological identity of theIL-22 polypeptide are accomplished by selecting substitutions thatdiffer significantly in their effect on maintaining (a) the structure ofthe polypeptide backbone in the area of the substitution, for example,as a sheet or helical conformation, (b) the charge of hydrophobicity ofthe molecule at the target site, or (c) the bulk of the side chain.Naturally occurring residues are divided into groups based on commonside-chain properties:

-   (1) hydrophobic: norleucine, met, ala, val, leu, ile;-   (2) neutral hydrophilic: cys, ser, thr;-   (3) acidic: asp, glu;-   (4) basic: asn, gin, his, lys, arg;-   (5) residues that influence chain orientation: gly, pro; and-   (6) aromatic: trp, tyr, phe.

Non-conservative substitutions will entail exchanging a member of one ofthese classes for another class. Such substituted residues also may beintroduced into the conservative substitution sites or, more preferably,into the remaining (non-conserved) sites.

The variations can be made using methods known in the art such asoligonucleotide-mediated (site-directed) mutagenesis, alanine scanning,and PCR mutagenesis. Site-directed mutagenesis [Carter et al., Nucl.Acids Res., 13:4331 (1986); Zoller et al., Nucl. Acids Res., 10:6487(1987)], cassette mutagenesis [Wells et al., Gene, 34:315 (1985)],restriction selection mutagenesis [Wells et al., Philos. Trans. R. Soc.London SerA, 317:415 (1986)] or other known techniques can be performedon the cloned DNA to produce the IL-22 variant DNA.

Scanning amino acid analysis can also be employed to identify one ormore amino acids along a contiguous sequence. Among the preferredscanning amino acids are relatively small, neutral amino acids. Suchamino acids include alanine, glycine, serine, and cysteine. Alanine istypically a preferred scanning amino acid among this group because iteliminates the side-chain beyond the beta-carbon and is less likely toalter the main-chain conformation of the variant [Cunningham and Wells,Science, 244: 1081–1085 (1989)]. Alanine is also typically preferredbecause it is the most common amino acid. Further, it is frequentlyfound in both buried and exposed positions [Creighton, The Proteins, (W.H. Freeman & Co., N.Y.); Chothia, J. Mol. Biol., 150:1 (1976)]. Ifalanine substitution does not yield adequate amounts of variant, anisoteric amino acid can be used.

C. Modifications of IL-22

Covalent modifications of IL-22 are included within the scope of thisinvention. One type of covalent modification includes reacting targetedamino acid residues of an IL-22 polypeptide with an organic derivatizingagent that is capable of reacting with selected side chains or the N- orC-terminal residues of the IL-22. Derivatization with bifunctionalagents is useful, for instance, for crosslinking IL-22 to awater-insoluble support matrix or surface for use in the method forpurifying anti-IL-22 antibodies, and vice-versa. Commonly usedcrosslinking agents include, e.g., 1,1-bis(diazoacetyl)-2-phenylethane,glutaraldehyde, N-hydroxysuccinimide esters, for example, esters with4-azidosalicylic acid, homobifunctional imidoesters, includingdisuccinimidyl esters such as 3,3′-dithiobis(succinimidylpropionate),bifunctional maleimides such as bis-N-maleimido-1,8-octane and agentssuch as methyl-3-[(p-azidophenyl)dithio]propioimidate.

Other modifications include deamidation of glutaminyl and asparaginylresidues to the corresponding glutamyl and aspartyl residues,respectively, hydroxylation of proline and lysine, phosphorylation ofhydroxyl groups of seryl or threonyl residues, methylation of theα-amino groups of lysine, arginine, and histidine side chains [T. E.Creighton, Proteins: Structure and Molecular Properties, W. H. Freeman &Co., San Francisco, pp. 79–86 (1983)], acetylation of the N-terminalamine, and amidation of any C-terminal carboxyl group.

Another type of covalent modification of the IL-22 polypeptide includedwithin the scope of this invention comprises altering the nativeglycosylation pattern of the polypeptide. “Altering the nativeglycosylation pattern” is intended for purposes herein to mean deletingone or more carbohydrate moieties found in native sequence IL-22 (eitherby removing the underlying glycosylation site or by deleting theglycosylation by chemical and/or enzymatic means), and/or adding one ormore glycosylation sites that are not present in the native sequenceIL-22. In addition, the phrase includes qualitative changes in theglycosylation of the native proteins, involving a change in the natureand proportions of the various carbohydrate moieties present.

Addition of glycosylation sites to the IL-22 polypeptide may beaccomplished by altering the amino acid sequence. The alteration may bemade, for example, by the addition of, or substitution by, one or moreserine or threonine residues to the native sequence IL-22 (for O-linkedglycosylation sites). The IL-22 amino acid sequence may optionally bealtered through changes at the DNA level, particularly by mutating theDNA encoding the IL-22 polypeptide at preselected bases such that codonsare generated that will translate into the desired amino acids.

Another means of increasing the number of carbohydrate moieties on theIL-22 polypeptide is by chemical or enzymatic coupling of glycosides tothe polypeptide. Such methods are described in the art, e.g., in WO87/05330 published 11 Sep. 1987, and in Aplin and Wriston, CRC Crit.Rev. Biochem., pp. 259–306 (1981).

Removal of carbohydrate moieties present on the IL-22 polypeptide may beaccomplished chemically or enzymatically or by mutational substitutionof codons encoding for amino acid residues that serve as targets forglycosylation. Chemical deglycosylation techniques are known in the artand described, for instance, by Hakimuddin, et al., Arch. Biochem.Biophys., 259:52 (1987) and by Edge et al., Anal. Biochem., 118:131(1981). Enzymatic cleavage of carbohydrate moieties on polypeptides canbe achieved by the use of a variety of endo- and exo-glycosidases asdescribed by Thotakura et al., Meth. Enzymol., 138:350 (1987).

Another type of covalent modification of IL-22 comprises linking theIL-22 polypeptide to one of a variety of nonproteinaceous polymers,e.g., polyethylene glycol (PEG), polypropylene glycol, orpolyoxyalkylenes, in the manner set forth in U.S. Pat. Nos. 4,640,835;4,496,689; 4,301,144; 4,670,417; 4,791,192 or 4,179,337.

The IL-22 of the present invention may also be modified in a way to forma chimeric molecule comprising IL-22 fused to another, heterologouspolypeptide or amino acid sequence.

In one embodiment, such a chimeric molecule comprises a fusion of theIL-22 with a tag polypeptide which provides an epitope to which ananti-tag antibody can selectively bind. The epitope tag is generallyplaced at the amino- or carboxyl- terminus of the IL-22. The presence ofsuch epitope-tagged forms of the IL-22 can be detected using an antibodyagainst the tag polypeptide. Also, provision of the epitope tag enablesthe IL-22 to be readily purified by affinity purification using ananti-tag antibody or another type of affinity matrix that binds to theepitope tag. Various tag polypeptides and their respective antibodiesare well known in the art. Examples include poly-histidine (poly-his) orpoly-histidine-glycine (poly-his-gly) tags; the flu HA tag polypeptideand its antibody 12CA5 [Field et al., Mol. Cell. Biol., 8:2159–2165(1988)]; the c-myc tag and the 8F9, 3C7, 6E10, G4, B7 and 9E10antibodies thereto [Evan et al., Molecular and Cellular Biology,5:3610–3616 (1985)]; and the Herpes Simplex virus glycoprotein D (gD)tag and its antibody [Paborsky et al., Protein Engineering, 3(6):547–553(1990)]. Other tag polypeptides include the Flag-peptide [Hopp et al.,BioTechnology, 6:1204–1210 (1988)]; the KT3 epitope peptide [Martin etal., Science, 255:192–194 (1992)]; an α-tubulin epitope peptide [Skinneret al., J. Biol. Chem., 266: 15163–15166 (1991)]; and the T7 gene 10protein peptide tag [Lutz-Freyermuth et al., Proc. Natl. Acad. Sci. USA,87:6393–6397 (1990)].

In an alternative embodiment, the chimeric molecule may comprise afusion of the IL-22 with an immunoglobulin or a particular region of animmunoglobulin. For a bivalent form of the chimeric molecule (alsoreferred to as an “immunoadhesin”), such a fusion could be to the Fcregion of an IgG molecule. The Ig fusions preferably include thesubstitution of a soluble (transmembrane domain deleted or inactivated)form of an IL-22 polypeptide in place of at least one variable regionwithin an Ig molecule. In a particularly preferred embodiment, theimmunoglobulin fusion includes the hinge, CH2 and CH3, or the hinge,CH1, CH2 and CH3 regions of an IgG1 molecule. For the production ofimmunoglobulin fusions see also U.S. Pat. No. 5,428,130 issued Jun. 27,1995.

D. Preparation of IL-22

The description below relates primarily to production of IL-22 byculturing cells transformed or transfected with a vector containingIL-22 nucleic acid. It is, of course, contemplated that alternativemethods, which are well known in the art, may be employed to prepareIL-22. For instance, the IL-22 sequence, or portions thereof, may beproduced by direct peptide synthesis using solid-phase techniques [see,e.g., Stewart et al., Solid-Phase Peptide Synthesis, W. H. Freeman Co.,San Francisco, Calif. (1969); Merrifield, J. Am. Chem. Soc, 85:2149–2154(1963)]. In vitro protein synthesis may be performed using manualtechniques or by automation. Automated synthesis may be accomplished,for instance, using an Applied Biosystems Peptide Synthesizer (FosterCity, Calif.) using manufacturer's instructions. Various portions of theIL-22 may be chemically synthesized separately and combined usingchemical or enzymatic methods to produce the full-length IL-22.

1. Isolation of DNA Encoding IL-22

DNA encoding IL-22 may be obtained from a cDNA library prepared fromtissue believed to possess the IL-22 mRNA and to express it at adetectable level. Accordingly, human IL-22 DNA can be convenientlyobtained from a cDNA library prepared from human tissue, such asdescribed in the Examples. The IL-22-encoding gene may also be obtainedfrom a genomic library or by known synthetic procedures (e.g., automatednucleic acid synthesis).

Libraries can be screened with probes (such as antibodies to the IL-22or oligonucleotides of at least about 20–80 bases) designed to identifythe gene of interest or the protein encoded by it. Screening the cDNA orgenomic library with the selected probe may be conducted using standardprocedures, such as described in Sambrook et al., Molecular Cloning: ALaboratory Manual (New York: Cold Spring Harbor Laboratory Press, 1989).An alternative means to isolate the gene encoding IL-22 is to use PCRmethodology [Sambrook et al., supra; Dieffenbach et al., PCR Primer: ALaboratory Manual (Cold Spring Harbor Laboratory Press, 1995)].

The Examples below describe techniques for screening a cDNA library. Theoligonucleotide sequences selected as probes should be of sufficientlength and sufficiently unambiguous that false positives are minimized.The oligonucleotide is preferably labeled such that it can be detectedupon hybridization to DNA in the library being screened. Methods oflabeling are well known in the art, and include the use of radiolabelslike ³²P-labeled ATP, biotinylation or enzyme labeling. Hybridizationconditions, including moderate stringency and high stringency, areprovided in Sambrook et al., supra.

Sequences identified in such library screening methods can be comparedand aligned to other known sequences deposited and available in publicdatabases such as GenBank or other private sequence databases. Sequenceidentity (at either the amino acid or nucleotide level) within definedregions of the molecule or across the full-length sequence can bedetermined using methods known in the art and as described herein.

Nucleic acid having protein coding sequence may be obtained by screeningselected cDNA or genomic libraries using the deduced amino acid sequencedisclosed herein for the first time, and, if necessary, usingconventional primer extension procedures as described in Sambrook etal., supra, to detect precursors and processing intermediates of mRNAthat may not have been reverse-transcribed into cDNA.

2. Selection and Transformation of Host Cells

Host cells are transfected or transformed with expression or cloningvectors described herein for IL-22 production and cultured inconventional nutrient media modified as appropriate for inducingpromoters, selecting transformants, or amplifying the genes encoding thedesired sequences. The culture conditions, such as media, temperature,pH and the like, can be selected by the skilled artisan without undueexperimentation. In general, principles, protocols, and practicaltechniques for maximizing the productivity of cell cultures can be foundin Mammalian Cell Biotechnology: a Practical Approach, M. Butler, ed.(IRL Press, 1991) and Sambrook et al., supra.

Methods of eukaryotic cell transfection and prokaryotic celltransformation are known to the ordinarily skilled artisan, for example,CaCl₂, CaPO₄, liposome-mediated and electroporation. Depending on thehost cell used, transformation is performed using standard techniquesappropriate to such cells. The calcium treatment employing calciumchloride, as described in Sambrook et al., supra, or electroporation isgenerally used for prokaryotes. Infection with Agrobacterium tumefaciensis used for transformation of certain plant cells, as described by Shawet al., Gene, 23:315 (1983) and WO 89/05859 published 29 Jun. 1989. Formammalian cells without such cell walls, the calcium phosphateprecipitation method of Graham and van der Eb, Virology, 52:456–457(1978) can be employed. General aspects of mammalian cell host systemtransfections have been described in U.S. Pat. No. 4,399,216.Transformations into yeast are typically carried out according to themethod of Van Solingen et al., J. Bact., 130:946 (1977) and Hsiao etal., Proc. Natl. Acad. Sci. (USA), 76:3829 (1979). However, other methodfor introducing DNA into cells, such as by nuclear microinjection,electroporation, bacterial protoplast fusion with intact cells, orpolycations, e.g., polybrene, polyornithine, may also be used. Forvarious techniques for transforming mammalian cells, see Keown et al.,Methods in Enzymology, 185:527–537 (1990) and Mansour et al., Nature,336:348–352 (1988).

Suitable host cells for cloning or expressing the DNA in the vectorsherein include prokaryote, yeast, or higher eukaryote cells. Suitableprokaryotes include but are not limited to eubacteria, such asGram-negative or Gram-positive organisms, for example,Enterobacteriaceae such as E. coli. Various E. coli strains are publiclyavailable, such as E. coli K12 strain MM294 (ATCC 31,446); E. coli X1776(ATCC 31,537); E. coli strain W3110 (ATCC 27,325) and K5772 (ATCC53,635). Other suitable prokaryotic host cells includeEnterobacteriaceae such as Escherichia, e.g., E. coli, Enterobacter,Erwinia, Klebsiella, Proteus, Salmonella, e.g., Salmonella typhimurium,Serratia, e.g., Serratia marcescans, and Shigella, as well as Bacillisuch as B. subtilis and B. licheniformis (e.g., B. licheniformis 41Pdisclosed in DD 266,710 published 12 Apr. 1989), Pseudomonas such as P.aeruginosa, and Streptomyces. These examples are illustrative ratherthan limiting. Strain W3110 is one particularly preferred host or parenthost because it is a common host strain for recombinant DNA productfermentations. Preferably, the host cell secretes minimal amounts ofproteolytic enzymes. For example, strain W3110 may be modified to effecta genetic mutation in the genes encoding proteins endogenous to thehost, with examples of such hosts including E. coli W3110 strain 1A2,which has the complete genotype tonA ; E. coli W3110 strain 9E4, whichhas the complete genotype tonA ptr3; E. coli W3110 strain 27C7 (ATCC55,244), which has the complete genotype tonA ptr3 phoA E15(argF-lac)169 deg PompT kan^(r) ; E. coli W3110 strain 37D6, which hasthe complete genotype tonA ptr3 phoA E15 (argF-lac)169 degP ompT rbs7ilvG kan^(r) ; E. coli W3110 strain 40B4, which is strain 37D 6 with anon-kanamycin resistant degP deletion mutation; and an E. coli strainhaving mutant periplasmic protease disclosed in U.S. Pat. No. 4,946,783issued 7 Aug. 1990. Alternatively, in vitro methods of cloning, e.g.,PCR or other nucleic acid polymerase reactions, are suitable.

In addition to prokaryotes, eukaryotic microbes such as filamentousfungi or yeast are suitable cloning or expression hosts forIL-22-encoding vectors. Saccharomyces cerevisiae is a commonly usedlower eukaryotic host microorganism. Others include Schizosaccharomycespombe (Beach and Nurse, Nature, 290: 140 [1981]; EP 139,383 published 2May 1985); Kluyveromyces hosts (U.S. Pat. No. 4,943,529; Fleer et al.,Bio/Technology, 9:968–975 (1991)) such as, e.g., K. lactis (MW98-8C,CBS683, CBS4574; Louvencourt et al., J. Bacteriol., 154(2):737–742[1983]), K. fragilis (ATCC 12,424), K. bulgaricus (ATCC 16,045), K.wickeramii (ATCC 24,178), K. waltii (ATCC 56,500), K. drosophilaruin(ATCC 36,906; Van den Berg et al., Bio/Technology, 8:135 (1990)), K.thermotolerans, and K. marxianus; yarrowia (EP 402,226); Pichia pastoris(EP 183,070; Sreekrishna et al., J Basic Microbiol., 28:265–278 [1988]);Candida; Trichoderma reesia (EP 244,234); Neurospora crassa (Case et alProc. Natl. Acad. Sci. USA, 76:5259–5263 [1979]); Schwanniomyces such asSchwanniomyces occidentalis (EP 394,538 published 31 Oct. 1990); andfilamentous fungi such as, e.g., Neurospora, Penicillium, Tolypocladium(WO 91/00357 published 10 Jan. 1991), and Aspergillus hosts such as A.nidulans (Ballance et al., Biochem. Biophys. Res. Commun., 112:284–289[1983]; Tilburn et al., Gene, 26:205–221 [1983]; Yelton et al., Proc.Natl. Acad. Sci. USA, 81:1470–1474 [1984]) and A. niger (Kelly andHynes, EMBO J., 4:475–479 [1985]). Methylotropic yeasts are suitableherein and include, but are not limited to, yeast capable of growth onmethanol selected from the genera consisting of Hansenula, Candida,Kloeckera, Pichia, Saccharomyces, Torulopsis, and Rhodotorula. A list ofspecific species that are exemplary of this class of yeasts may be foundin C. Anthony, The Biochemistry of Methylotrophs, 269 (1982).

Suitable host cells for the expression of glycosylated IL-22 are derivedfrom multicellular organisms. Examples of invertebrate cells includeinsect cells such as Drosophila S2 and Spodoptera Sf9, as well as plantcells. Examples of useful mammalian host cell lines include Chinesehamster ovary (CHO) and COS cells. More specific examples include monkeykidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1651); humanembryonic kidney line (293 or 293 cells subcloned for growth insuspension culture, Graham et al., J. Gen Virol., 36:59 (1977)); Chinesehamster ovary cells/-DHFR(CHO, Urlaub and Chasin, Proc. Natl. Acad. Sci.USA, 77:4216 (1980)); mouse sertoli cells (TM4, Mather, Biol. Reprod.,23:243–251 (1980)); human lung cells (W138, ATCC CCL 75); human livercells (Hep G2, HB 8065); and mouse mammary tumor (MMT 060562, ATCCCCL51). The selection of the appropriate host cell is deemed to bewithin the skill in the art.

3. Selection and Use of a Replicable Vector

The nucleic acid (e.g., cDNA or genomic DNA) encoding IL-22 may beinserted into a replicable vector for cloning (amplification of the DNA)or for expression. Various vectors are publicly available. The vectormay, for example, be in the form of a plasmid, cosmid, viral particle,or phage. The appropriate nucleic acid sequence may be inserted into thevector by a variety of procedures. In general, DNA is inserted into anappropriate restriction endonuclease site(s) using techniques known inthe art. Vector components generally include, but are not limited to,one or more of a signal sequence, an origin of replication, one or moremarker genes, an enhancer element, a promoter, and a transcriptiontermination sequence. Construction of suitable vectors containing one ormore of these components employs standard ligation techniques which areknown to the skilled artisan.

The IL-22 may be produced recombinantly not only directly, but also as afusion polypeptide with a heterologous polypeptide, which may be asignal sequence or other polypeptide having a specific cleavage site atthe N-terminus of the mature protein or polypeptide. In general, thesignal sequence may be a component of the vector, or it may be a part ofthe IL-22-encoding DNA that is inserted into the vector. The signalsequence may be a prokaryotic signal sequence selected, for example,from the group of the alkaline phosphatase, penicillinase, lpp, orheat-stable enterotoxin II leaders. For yeast secretion the signalsequence may be, e.g., the yeast invertase leader, alpha factor leader(including Saccharoinyces and Kluyveromyces α-factor leaders, the latterdescribed in U.S. Pat. No. 5,010,182), or acid phosphatase leader, theC. albicans glucoamylase leader (EP 362,179 published 4 Apr. 1990), orthe signal described in WO 90/13646 published 15 Nov. 1990. In mammaliancell expression, mammalian signal sequences may be used to directsecretion of the protein, such as signal sequences from secretedpolypeptides of the same or related species, as well as viral secretoryleaders.

Both expression and cloning vectors contain a nucleic acid sequence thatenables the vector to replicate in one or more selected host cells. Suchsequences are well known for a variety of bacteria, yeast, and viruses.The origin of replication from the plasmid pBR322 is suitable for mostGram-negative bacteria, the 2μ plasmid origin is suitable for yeast, andvarious viral origins (SV40, polyoma, adenovirus, VSV or BPV) are usefulfor cloning vectors in mammalian cells.

Expression and cloning vectors will typically contain a selection gene,also termed a selectable marker. Typical selection genes encode proteinsthat (a) confer resistance to antibiotics or other toxins, e.g.,ampicillin, neomycin, methotrexate, or tetracycline, (b) complementauxotrophic deficiencies, or (c) supply critical nutrients not availablefrom complex media, e.g., the gene encoding D-alanine racemase forBacilli.

An example of suitable selectable markers for mammalian cells are thosethat enable the identification of cells competent to take up theIL-22-encoding nucleic acid, such as DHFR or thymidine kinase. Anappropriate host cell when wild-type DHFR is employed is the CHO cellline deficient in DHFR activity, prepared and propagated as described byUrlaub et al., Proc. Natl. Acad. Sci. USA, 77:4216 (1980). A suitableselection gene for use in yeast is the trp1 gene present in the yeastplasmid YRp7 [Stinchcomb et al., Nature, 282:39 (1979); Kingsman et al.,Gene, 7:141 (1979); Tschemper et al., Gene, 10:157 (1980)]. The trp1gene provides a selection marker for a mutant strain of yeast lackingthe ability to grow in tryptophan, for example, ATCC No. 44076 or PEP4-1[Jones, Genetics, 85:12 (1977)].

Expression and cloning vectors usually contain a promoter operablylinked to the IL-22-encoding nucleic acid sequence to direct mRNAsynthesis. Promoters recognized by a variety of potential host cells arewell known. Promoters suitable for use with prokaryotic hosts includethe β-lactamase and lactose promoter systems [Chang et al., Nature,275:615 (1978); Goeddel et al., Nature, 281:544 (1979)], alkalinephosphatase, a tryptophan (trp) promoter system [Goeddel, Nucleic AcidsRes., 8:4057 (1980); EP 36,776], and hybrid promoters such as the tacpromoter [deBoer et al., Proc. Natl. Acad. Sci. USA, 80:21–25 (1983)].Promoters for use in bacterial systems also will contain aShine-Dalgarno (S.D.) sequence operably linked to the DNA encodingIL-22.

Examples of suitable promoting sequences for use with yeast hostsinclude the promoters for 3-phosphoglycerate kinase [Hitzeman et al., J.Biol. Chem., 255:2073 (1980)] or other glycolytic enzymes [Hess et al.,J. Adv. Enzyme Reg., 7:149 (1968); Holland, Biochemistry, 17:4900(1978)], such as enolase, glyceraldehyde-3-phosphate dehydrogenase,hexokinase, pyruvate decarboxylase, phosphofructokinase,glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvatekinase, triosephosphate isomerase, phosphoglucose isomerase, andglucokinase.

Other yeast promoters, which are inducible promoters having theadditional advantage of transcription controlled by growth conditions,are the promoter regions for alcohol dehydrogenase 2, isocytochrome C,acid phosphatase, degradative enzymes associated with nitrogenmetabolism, metallothionein, glyceraldehyde-3-phosphate dehydrogenase,and enzymes responsible for maltose and galactose utilization. Suitablevectors and promoters for use in yeast expression are further describedin EP 73,657.

IL-22 transcription from vectors in mammalian host cells is controlled,for example, by promoters obtained from the genomes of viruses such aspolyoma virus, fowlpox virus (UK 2,211,504 published 5 Jul. 1989),adenovirus (such as Adenovirus 2), bovine papilloma virus, avian sarcomavirus, cytomegalovirus, a retrovirus, hepatitis-B virus and Simian Virus40 (SV40), from heterologous mammalian promoters, e.g., the actinpromoter or an immunoglobulin promoter, and from heat-shock promoters,provided such promoters are compatible with the host cell systems.

Transcription of a DNA encoding the IL-22 by higher eukaryotes may beincreased by inserting an enhancer sequence into the vector. Enhancersare cis-acting elements of DNA, usually about from 10 to 300 bp, thatact on a promoter to increase its transcription. Many enhancer sequencesare now known from mammalian genes (globin, elastase, albumin,α-fetoprotein, and insulin). Typically, however, one will use anenhancer from a eukaryotic cell virus. Examples include the SV40enhancer on the late side of the replication origin (bp 100–270), thecytomegalovirus early promoter enhancer, the polyoma enhancer on thelate side of the replication origin, and adenovirus enhancers. Theenhancer may be spliced into the vector at a position 5′ or 3′ to theIL-22 coding sequence, but is preferably located at a site 5′ from thepromoter.

Expression vectors used in eukaryotic host cells (yeast, fungi, insect,plant, animal, human, or nucleated cells from other multicellularorganisms) will also contain sequences necessary for the termination oftranscription and for stabilizing the mRNA. Such sequences are commonlyavailable from the 5′ and, occasionally 3′, untranslated regions ofeukaryotic or viral DNAs or cDNAs. These regions contain nucleotidesegments transcribed as polyadenylated fragments in the untranslatedportion of the mRNA encoding IL-22.

Still other methods, vectors, and host cells suitable for adaptation tothe synthesis of IL-22 in recombinant vertebrate cell culture aredescribed in Gething et al., Nature, 293:620–625 (1981); Mantei et al.,Nature, 281:40 –46 (1979); EP 117,060; and EP 117,058.

4. Detecting Gene Amplification/Expression

Gene amplification and/or expression may be measured in a sampledirectly, for example, by conventional Southern blotting, Northernblotting to quantitate the transcription of mRNA [Thomas, Proc. Natl.Acad. Sci. USA, 77:5201–5205 (1980)], dot blotting (DNA analysis), or insitu hybridization, using an appropriately labeled probe, based on thesequences provided herein. Alternatively, antibodies may be employedthat can recognize specific duplexes, including DNA duplexes, RNAduplexes, and DNA-RNA hybrid duplexes or DNA-protein duplexes. Theantibodies in turn may be labeled and the assay may be carried out wherethe duplex is bound to a surface, so that upon the formation of duplexon the surface, the presence of antibody bound to the duplex can bedetected.

Gene expression, alternatively, may be measured by immunologicalmethods, such as immunohistochemical staining of cells or tissuesections and assay of cell culture or body fluids, to quantitatedirectly the expression of gene product. Antibodies useful forimmunohistochemical staining and/or assay of sample fluids may be eithermonoclonal or polyclonal, and may be prepared in any mammal.Conveniently, the antibodies may be prepared against a native sequenceIL-22 polypeptide or against a synthetic peptide based on the DNAsequences provided herein or against exogenous sequence fused to IL-22DNA and encoding a specific antibody epitope.

5. Purification of Polypeptide

Forms of IL-22 may be recovered from culture medium or from host celllysates. If membrane-bound, it can be released from the membrane using asuitable detergent solution (e.g. Triton-X 100) or by enzymaticcleavage. Cells employed in expression of IL-22 can be disrupted byvarious physical or chemical means, such as freeze-thaw cycling,sonication, mechanical disruption, or cell lysing agents.

It may be desired to purify IL-22 from recombinant cell proteins orpolypeptides. The following procedures are exemplary of suitablepurification procedures: by fractionation on an ion-exchange column;ethanol precipitation; reverse phase HPLC; chromatography on silica oron a cation-exchange resin such as DEAE; chromatofocusing; SDS-PAGE;ammonium sulfate precipitation; gel filtration using, for example,Sephadex G-75; protein A Sepharose columns to remove contaminants suchas IgG; and metal chelating columns to bind epitope-tagged forms of theIL-22. Various methods of protein purification may be employed and suchmethods are known in the art and described for example in Deutscher,Methods in Enzymology, 182 (1990); Scopes, Protein Purification:Principles and Practice, Springer-Verlag, New York (1982). Thepurification step(s) selected will depend, for example, on the nature ofthe production process used and the particular IL-22 produced.

E. Uses for IL-22

Nucleotide sequences (or their complement) encoding IL-22 have variousapplications in the art of molecular biology, including uses ashybridization probes, in chromosome and gene mapping and in thegeneration of anti-sense RNA and DNA. IL-22 nucleic acid will also beuseful for the preparation of IL-22 polypeptides by the recombinanttechniques described herein.

The full-length native sequence IL-22 gene, or portions thereof, may beused as hybridization probes for a cDNA library to isolate thefull-length IL-22 cDNA or to isolate still other cDNAs (for instance,those encoding naturally-occurring variants of IL-22 or IL-22 from otherspecies) which have a desired sequence identity to the native IL-22sequence disclosed herein. Optionally, the length of the probes will beabout 20 to about 50 bases. The hybridization probes may be derived fromat least partially novel regions of the full length native nucleotidesequence wherein those regions may be determined without undueexperimentation or from genomic sequences including promoters, enhancerelements and introns of native sequence IL-22. By way of example, ascreening method will comprise isolating the coding region of the IL-22gene using the known DNA sequence to synthesize a selected probe ofabout 40 bases. Hybridization probes may be labeled by a variety oflabels, including radionucleotides such as ³²P or ³⁵S, or enzymaticlabels such as alkaline phosphatase coupled to the probe viaavidin/biotin coupling systems. Labeled probes having a sequencecomplementary to that of the IL-22 gene of the present invention can beused to screen libraries of human cDNA, genomic DNA or mRNA to determinewhich members of such libraries the probe hybridizes to. Hybridizationtechniques are described in further detail in the Examples below.

Any EST sequences disclosed in the present application may similarly beemployed as probes, using the methods disclosed herein.

Other useful fragments of the IL-22 nucleic acids include antisense orsense oligonucleotides comprising a singe-stranded nucleic acid sequence(either RNA or DNA) capable of binding to target IL-22 mRNA (sense) orIL-22 DNA (antisense) sequences. Antisense or sense oligonucleotides,according to the present invention, comprise a fragment of the codingregion of IL-22 DNA. Such a fragment generally comprises at least about14 nucleotides, preferably from about 14 to 30 nucleotides. The abilityto derive an antisense or a sense oligonucleotide, based upon a cDNAsequence encoding a given protein is described in, for example, Steinand Cohen (Cancer Res. 48:2659, 1988) and van der Krol et al.(BioTechniques 6:958, 1988).

Binding of antisense or sense oligonucleotides to target nucleic acidsequences results in the formation of duplexes that block transcriptionor translation of the target sequence by one of several means, includingenhanced degradation of the duplexes, premature termination oftranscription or translation, or by other means. The antisenseoligonucleotides thus may be used to block expression of IL-22 proteins.Antisense or sense oligonucleotides further comprise oligonucleotideshaving modified sugar-phosphodiester backbones (or other sugar linkages,such as those described in WO 91/06629) and wherein such sugar linkagesare resistant to endogenous nucleases. Such oligonucleotides withresistant sugar linkages are stable in vivo (i.e., capable of resistingenzymatic degradation) but retain sequence specificity to be able tobind to target nucleotide sequences.

Other examples of sense or antisense oligonucleotides include thoseoligonucleotides which are covalently linked to organic moieties, suchas those described in WO 90/10048, and other moieties that increasesaffinity of the oligonucleotide for a target nucleic acid sequence, suchas poly-(L-lysine). Further still, intercalating agents, such asellipticine, and alkylating agents or metal complexes may be attached tosense or antisense oligonucleotides to modify binding specificities ofthe antisense or sense oligonucleotide for the target nucleotidesequence.

Antisense or sense oligonucleotides may be introduced into a cellcontaining the target nucleic acid sequence by any gene transfer method,including, for example, CaPO₄-mediated DNA transfection,electroporation, or by using gene transfer vectors such as Epstein-Barrvirus. In a preferred procedure, an antisense or sense oligonucleotideis inserted into a suitable retroviral vector. A cell containing thetarget nucleic acid sequence is contacted with the recombinantretroviral vector, either in vivo or ex vivo. Suitable retroviralvectors include, but are not limited to, those derived from the murineretrovirus M-MuLV, N2 (a retrovirus derived from M-MuLV), or the doublecopy vectors designated DCT5A, DCT5B and DCT5C (see WO 90/13641).

Sense or antisense oligonucleotides also may be introduced into a cellcontaining the target nucleotide sequence by formation of a conjugatewith a ligand binding molecule, as described in WO 91/04753. Suitableligand binding molecules include, but are not limited to, cell surfacereceptors, growth factors, other cytokines, or other ligands that bindto cell surface receptors. Preferably, conjugation of the ligand bindingmolecule does not substantially interfere with the ability of the ligandbinding molecule to bind to its corresponding molecule or receptor, orblock entry of the sense or antisense oligonucleotide or its conjugatedversion into the cell.

Alternatively, a sense or an antisense oligonucleotide may be introducedinto a cell containing the target nucleic acid sequence by formation ofan oligonucleotide-lipid complex, as described in WO 90/10448. The senseor antisense oligonucleotide-lipid complex is preferably dissociatedwithin the cell by an endogenous lipase.

Antisense or sense RNA or DNA molecules are generally at least about 5bases in length, about 10 bases in length, about 15 bases in length,about 20 bases in length, about 25 bases in length, about 30 bases inlength, about 35 bases in length, about 40 bases in length, about 45bases in length, about 50 bases in length, about 55 bases in length,about 60 bases in length, about 65 bases in length, about 70 bases inlength, about 75 bases in length, about 80 bases in length, about 85bases in length, about 90 bases in length, about 95 bases in length,about 100 bases in length, or more.

The probes may also be employed in PCR techniques to generate a pool ofsequences for identification of closely related IL-22 coding sequences.

Nucleotide sequences encoding an IL-22 can also be used to constructhybridization probes for mapping the gene which encodes that IL-22 andfor the genetic analysis of individuals with genetic disorders. Thenucleotide sequences provided herein may be mapped to a chromosome andspecific regions of a chromosome using known techniques, such as in situhybridization, linkage analysis against known chromosomal markers, andhybridization screening with libraries.

When the coding sequences for IL-22 encode a protein which binds toanother protein (example, where the IL-22 is a receptor), the IL-22 canbe used in assays to identify the other proteins or molecules involvedin the binding interaction. By such methods, inhibitors of thereceptor/ligand binding interaction can be identified. Proteins involvedin such binding interactions can also be used to screen for peptide orsmall molecule inhibitors or agonists of the binding interaction. Also,the receptor IL-22 can be used to isolate correlative ligand(s).Screening assays can be designed to find lead compounds that mimic thebiological activity of a native IL-22 or a receptor for IL-22. Suchscreening assays will include assays amenable to high-throughputscreening of chemical libraries, making them particularly suitable foridentifying small molecule drug candidates. Small molecules contemplatedinclude synthetic organic or inorganic compounds. The assays can beperformed in a variety of formats, including protein-protein bindingassays, biochemical screening assays, immunoassays and cell basedassays, which are well characterized in the art.

Nucleic acids which encode IL-22 or its modified forms can also be usedto generate either transgenic animals or “knock out” animals which, inturn, are useful in the development and screening of therapeuticallyuseful reagents. A transgenic animal (e.g., a mouse or rat) is an animalhaving cells that contain a transgene, which transgene was introducedinto the animal or an ancestor of the animal at a prenatal, e.g., anembryonic stage. A transgene is a DNA which is integrated into thegenome of a cell from which a transgenic animal develops. In oneembodiment, cDNA encoding IL-22 can be used to clone genomic DNAencoding IL-22 in accordance with established techniques and the genomicsequences used to generate transgenic animals that contain cells whichexpress DNA encoding IL-22. Methods for generating transgenic animals,particularly animals such as mice or rats, have become conventional inthe art and are described, for example, in U.S. Pat. Nos. 4,736,866 and4,870,009. Typically, particular cells would be targeted for IL-22transgene incorporation with tissue-specific enhancers. Transgenicanimals that include a copy of a transgene encoding IL-22 introducedinto the germ line of the animal at an embryonic stage can be used toexamine the effect of increased expression of DNA encoding IL-22. Suchanimals can be used as tester animals for reagents thought to conferprotection from, for example, pathological conditions associated withits overexpression. In accordance with this facet of the invention, ananimal is treated with the reagent and a reduced incidence of thepathological condition, compared to untreated animals bearing thetransgene, would indicate a potential therapeutic intervention for thepathological condition.

Alternatively, non-human homologues of IL-22 can be used to construct anIL-22 “knock out” animal which has a defective or altered gene encodingIL-22 as a result of homologous recombination between the endogenousgene encoding IL-22 and altered genomic DNA encoding IL-22 introducedinto an embryonic stem cell of the animal. For example, cDNA encodingIL-22 can be used to clone genomic DNA encoding IL-22 in accordance withestablished techniques. A portion of the genomic DNA encoding IL-22 canbe deleted or replaced with another gene, such as a gene encoding aselectable marker which can be used to monitor integration. Typically,several kilobases of unaltered flanking DNA (both at the 5′ and 3′ ends)are included in the vector [see e.g., Thomas and Capecchi, Cell, 51:503(1987) for a description of homologous recombination vectors]. Thevector is introduced into an embryonic stem cell line (e.g., byelectroporation) and cells in which the introduced DNA has homologouslyrecombined with the endogenous DNA are selected [see e.g., Li et al.,Cell, 69:915 (1992)]. The selected cells are then injected into ablastocyst of an animal (e.g., a mouse or rat) to form aggregationchimeras [see e.g., Bradley, in Teratocarcinomas and Embryonic StemCells: A Practical Approach, E. J. Robertson, ed. (IRL, Oxford, 1987),pp. 113–152]. A chimeric embryo can then be implanted into a suitablepseudopregnant female foster animal and the embryo brought to term tocreate a “knock out” animal. Progeny harboring the homologouslyrecombined DNA in their germ cells can be identified by standardtechniques and used to breed animals in which all cells of the animalcontain the homologously recombined DNA. Knockout animals can becharacterized for instance, for their ability to defend against certainpathological conditions and for their development of pathologicalconditions due to absence of the IL-22 polypeptide.

Nucleic acid encoding the IL-22 polypeptides may also be used in genetherapy. In gene therapy applications, genes are introduced into cellsin order to achieve in vivo synthesis of a therapeutically effectivegenetic product, for example for replacement of a defective gene. “Genetherapy” includes both conventional gene therapy where a lasting effectis achieved by a single treatment, and the administration of genetherapeutic agents, which involves the one time or repeatedadministration of a therapeutically effective DNA or mRNA. AntisenseRNAs and DNAs can be used as therapeutic agents for blocking theexpression of certain genes in vivo. It has already been shown thatshort antisense oligonucleotides can be imported into cells where theyact as inhibitors, despite their low intracellular concentrations causedby their restricted uptake by the cell membrane. (Zamecnik et al., Proc.Natl. Acad. Sci. USA 83:4143–4146 [1986]). The oligonucleotides can bemodified to enhance their uptake, e.g. by substituting their negativelycharged phosphodiester groups by uncharged groups.

There are a variety of techniques available for introducing nucleicacids into viable cells. The techniques vary depending upon whether thenucleic acid is transferred into cultured cells in vitro, or in vivo inthe cells of the intended host. Techniques suitable for the transfer ofnucleic acid into mammalian cells in vitro include the use of liposomes,electroporation, microinjection, cell fusion, DEAE-dextran, the calciumphosphate precipitation method, etc. The currently preferred in vivogene transfer techniques include transfection with viral (typicallyretroviral) vectors and viral coat protein-liposome mediatedtransfection (Dzau et al., Trends in Biotechnology 11, 205–210 [1993]).In some situations it is desirable to provide the nucleic acid sourcewith an agent that targets the target cells, such as an antibodyspecific for a cell surface membrane protein or the target cell, aligand for a receptor on the target cell, etc. Where liposomes areemployed, proteins which bind to a cell surface membrane proteinassociated with endocytosis may be used for targeting and/or tofacilitate uptake, e.g. capsid proteins or fragments thereof tropic fora particular cell type, antibodies for proteins which undergointernalization in cycling, proteins that target intracellularlocalization and enhance intracellular half-life. The technique ofreceptor-mediated endocytosis is described, for example, by Wu et al.,J. Biol. Chem. 262, 4429–4432 (1987); and Wagneret al., Proc. Natl.Acad. Sci. USA 87, 3410–3414 (1990). For review of gene marking and genetherapy protocols see Anderson et al., Science 256, 808–813 (1992).

The IL-22 polypeptides described herein may also be employed asmolecular weight markers for protein electrophoresis purposes and theisolated nucleic acid sequences may be used for recombinantly expressingthose markers.

The nucleic acid molecules encoding the IL-22 polypeptides or fragmentsthereof described herein are useful for chromosome identification. Inthis regard, there exists an ongoing need to identify new chromosomemarkers, since relatively few chromosome marking reagents, based uponactual sequence data are presently available. Each IL-22 nucleic acidmolecule of the present invention can be used as a chromosome marker.

The IL-22 polypeptides and nucleic acid molecules of the presentinvention may also be used diagnostically for tissue typing, wherein theIL-22 polypeptides of the present invention may be differentiallyexpressed in one tissue as compared to another, preferably in a diseasedtissue as compared to a normal tissue of the same tissue type. IL-22nucleic acid molecules will find use for generating probes for PCR,Northern analysis, Southern analysis and Western analysis.

The IL-22 polypeptides described herein may also be employed astherapeutic agents. The IL-22 polypeptides of the present invention canbe formulated according to known methods to prepare pharmaceuticallyuseful compositions, whereby the IL-22 product hereof is combined inadmixture with a pharmaceutically acceptable carrier vehicle.Therapeutic formulations are prepared for storage by mixing the activeingredient having the desired degree of purity with optionalphysiologically acceptable carriers, excipients or stabilizers(Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)),in the form of lyophilized formulations or aqueous solutions. Acceptablecarriers, excipients or stabilizers are nontoxic to recipients at thedosages and concentrations employed, and include buffers such asphosphate, citrate and other organic acids; antioxidants includingascorbic acid; low molecular weight (less than about 10 residues)polypeptides; proteins, such as serum albumin, gelatin orimmunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone,amino acids such as glycine, glutamine, asparagine, arginine or lysine;monosaccharides, disaccharides and other carbohydrates includingglucose, mannose, or dextrins; chelating agents such as EDTA; sugaralcohols such as mannitol or sorbitol; salt-forming counterions such assodium; and/or nonionic surfactants such as TWEEN™, PLURONICS™ or PEG.

The formulations to be used for in vivo administration must be sterile.This is readily accomplished by filtration through sterile filtrationmembranes, prior to or following lyophilization and reconstitution.

Therapeutic compositions herein generally are placed into a containerhaving a sterile access port, for example, an intravenous solution bagor vial having a stopper pierceable by a hypodermic injection needle.

The route of administration is in accord with known methods, e.g.injection or infusion by intravenous, intraperitoneal, intracerebral,intramuscular, intraocular, intraarterial or intralesional routes,topical administration, or by sustained release systems.

Dosages and desired drug concentrations of pharmaceutical compositionsof the present invention may vary depending on the particular useenvisioned. The determination of the appropriate dosage or route ofadministration is well within the skill of an ordinary physician. Animalexperiments provide reliable guidance for the determination of effectivedoses for human therapy. Interspecies scaling of effective doses can beperformed following the principles laid down by Mordenti, J. andChappell, W. “The use of interspecies scaling in toxicokinetics” InToxicokinetics and New Drug Development, Yacobi et al., Eds., PergamonPress, New York 1989, pp. 42–96.

When in vivo administration of an IL-22 polypeptide or agonist orantagonist thereof is employed, normal dosage amounts may vary fromabout 10 ng/kg to up to 100 mg/kg of mammal body weight or more per day,preferably about 1 μg/kg/day to 10 mg/kg/day, depending upon the routeof administration. Guidance as to particular dosages and methods ofdelivery is provided in the literature; see, for example, U.S. Pat. Nos.4,657,760; 5,206,344; or 5,225,212. It is anticipated that differentformulations will be effective for different treatment compounds anddifferent disorders, that administration targeting one organ or tissue,for example, may necessitate delivery in a manner different from that toanother organ or tissue.

Where sustained-release administration of an IL-22 polypeptide isdesired in a formulation with release characteristics suitable for thetreatment of any disease or disorder requiring administration of theIL-22 polypeptide, microencapsulation of the IL-22 polypeptide iscontemplated. Microencapsulation of recombinant proteins for sustainedrelease has been successfully performed with human growth hormone(rhGH), interferon- (rhIFN-), interleukin-2, and MN rgp120. Johnson etal., Nat. Med., 2:795–799(1996); Yasuda, Biomed. Ther.,27:1221–1223(1993); Hora et al., Bio/Technology, 8:755–758 (1990);Cleland, “Design and Production of Single Immunization Vaccines UsingPolylactide Polyglycolide Microsphere Systems,” in Vaccine Design: TheSubunit and Adjuvant Approach, Powell and Newman, eds, (Plenum Press:New York, 1995), pp. 439–462; WO 97/03692, WO 96/40072, WO 96/07399; andU.S. Pat. No. 5,654,010.

The sustained-release formulations of these proteins were developedusing poly-lactic-coglycolic acid (PLGA) polymer due to itsbiocompatibility and wide range of biodegradable properties. Thedegradation products of PLGA, lactic and glycolic acids, can be clearedquickly within the human body. Moreover, the degradability of thispolymer can be adjusted from months to years depending on its molecularweight and composition. Lewis, “Controlled release of bioactive agentsfrom lactide/glycolide polymer,” in: M. Chasin and R. Langer (Eds.),Biodegradable Polymers as Drug Delivery Systems (Marcel Dekker: NewYork, 1990), pp. 1–41.

This invention encompasses methods of screening compounds to identifythose that mimic the IL-22 polypeptide (agonists) or prevent the effectof the IL-22 polypeptide (antagonists). Screening assays for antagonistdrug candidates are designed to identify compounds that bind or complexwith the IL-22 polypeptides encoded by the genes identified herein, orotherwise interfere with the interaction of the encoded polypeptideswith other cellular proteins. Such screening assays will include assaysamenable to high-throughput screening of chemical libraries, making themparticularly suitable for identifying small molecule drug candidates.

The assays can be performed in a variety of formats, includingprotein-protein binding assays, biochemical screening assays,immunoassays, and cell-based assays, which are well characterized in theart.

All assays for antagonists are common in that they call for contactingthe drug candidate with an IL-22 polypeptide encoded by a nucleic acididentified herein under conditions and for a time sufficient to allowthese two components to interact.

In binding assays, the interaction is binding and the complex formed canbe isolated or detected in the reaction mixture. In a particularembodiment, the IL-22 polypeptide encoded by the gene identified hereinor the drug candidate is immobilized on a solid phase, e.g., on amicrotiter plate, by covalent or non-covalent attachments. Non-covalentattachment generally is accomplished by coating the solid surface with asolution of the IL-22 polypeptide and drying. Alternatively, animmobilized antibody, e.g., a monoclonal antibody, specific for theIL-22 polypeptide to be immobilized can be used to anchor it to a solidsurface. The assay is performed by adding the non-immobilized component,which may be labeled by a detectable label, to the immobilizedcomponent, e.g., the coated surface containing the anchored component.When the reaction is complete, the non-reacted components are removed,e.g., by washing, and complexes anchored on the solid surface aredetected. When the originally non-immobilized component carries adetectable label, the detection of label immobilized on the surfaceindicates that complexing occurred. Where the originally non-immobilizedcomponent does not carry a label, complexing can be detected, forexample, by using a labeled antibody specifically binding theimmobilized complex.

If the candidate compound interacts with but does not bind to aparticular IL-22 polypeptide encoded by a gene identified herein, itsinteraction with that polypeptide can be assayed by methods well knownfor detecting protein-protein interactions. Such assays includetraditional approaches, such as, e.g., cross-linking,co-immunoprecipitation, and co-purification through gradients orchroinatographic columns. In addition, protein-protein interactions canbe monitored by using a yeast-based genetic system described by Fieldsand co-workers (Fields and Song, Nature (London), 340:245–246 (1989);Chien et al., Proc. Natl. Acad. Sci. USA, 88:9578–9582 (1991) asdisclosed by Chevray and Nathans, Proc. Natl. Acad. Sci. USA, 89:5789–5793 (1991). Many transcriptional activators, such as yeast GAL4,consist of two physically discrete modular domains, one acting as theDNA-binding domain, the other one functioning as thetranscription-activation domain. The yeast expression system describedin the foregoing publications (generally referred to as the “two-hybridsystem”) takes advantage of this property, and employs two hybridproteins, one in which the target protein is fused to the DNA-bindingdomain of GAL4, and another, in which candidate activating proteins arefused to the activation domain. The expression of a GAL1-lacZ reportergene under control of a GAL4-activated promoter depends onreconstitution of GAL4 activity via protein-protein interaction.Colonies containing interacting polypeptides are detected with achromogenic substrate for β-galactosidase. A complete kit (MATCHMAKER™)for identifying protein-protein interactions between two specificproteins using the two-hybrid technique is commercially available fromClontech. This system can also be extended to map protein domainsinvolved in specific protein interactions as well as to pinpoint aminoacid residues that are crucial for these interactions.

Compounds that interfere with the interaction of a gene encoding anIL-22 polypeptide identified herein and other intra- or extracellularcomponents can be tested as follows: usually a reaction mixture isprepared containing the product of the gene and the intra- orextracellular component under conditions and for a time allowing for theinteraction and binding of the two products. To test the ability of acandidate compound to inhibit binding, the reaction is run in theabsence and in the presence of the test compound. In addition, a placebomay be added to a third reaction mixture, to serve as positive control.The binding (complex formation) between the test compound and the intra-or extracellular component present in the mixture is monitored asdescribed hereinabove. The formation of a complex in the controlreaction(s) but not in the reaction mixture containing the test compoundindicates that the test compound interferes with the interaction of thetest compound and its reaction partner.

To assay for antagonists, the IL-22 polypeptide may be added to a cellalong with the compound to be screened for a particular activity and theability of the compound to inhibit the activity of interest in thepresence of the IL-22 polypeptide indicates that the compound is anantagonist to the IL-22 polypeptide. Alternatively, antagonists may bedetected by combining the IL-22 polypeptide and a potential antagonistwith membrane-bound IL-22 polypeptide receptors or recombinant receptorsunder appropriate conditions for a competitive inhibition assay. TheIL-22 polypeptide can be labeled, such as by radioactivity, such thatthe number of IL-22 polypeptide molecules bound to the receptor can beused to determine the effectiveness of the potential antagonist. Thegene encoding the receptor can be identified by numerous methods knownto those of skill in the art, for example, ligand panning and FACSsorting. Coligan et al., Current Protocols in Immun., 1(2): Chapter 5(1991). Preferably, expression cloning is employed whereinpolyadenylated RNA is prepared from a cell responsive to the IL-22polypeptide and a cDNA library created from this RNA is divided intopools and used to transfect COS cells or other cells that are notresponsive to the IL-22 polypeptide. Transfected cells that are grown onglass slides are exposed to labeled IL-22 polypeptide. The IL-22polypeptide can be labeled by a variety of means including iodination orinclusion of a recognition site for a site-specific protein kinase.Following fixation and incubation, the slides are subjected toautoradiographic analysis. Positive pools are identified and sub-poolsare prepared and re-transfected using an interactive sub-pooling andre-screening process, eventually yielding a single clone that encodesthe putative receptor.

As an alternative approach for receptor identification, labeled IL-22polypeptide can be photoaffinity-linked with cell membrane or extractpreparations that express the receptor molecule. Cross-linked materialis resolved by PAGE and exposed to X-ray film. The labeled complexcontaining the receptor can be excised, resolved into peptide fragments,and subjected to protein micro-sequencing. The amino acid sequenceobtained from micro-sequencing would be used to design a set ofdegenerate oligonucleotide probes to screen a cDNA library to identifythe gene encoding the putative receptor.

In another assay for antagonists, mammalian cells or a membranepreparation expressing the receptor would be incubated with labeledIL-22 polypeptide in the presence of the candidate compound. The abilityof the compound to enhance or block this interaction could then bemeasured.

More specific examples of potential antagonists include anoligonucleotide that binds to the fusions of immunoglobulin with IL-22polypeptide, and, in particular, antibodies including, withoutlimitation, poly- and monoclonal antibodies and antibody fragments,single-chain antibodies, anti-idiotypic antibodies, and chimeric orhumanized versions of such antibodies or fragments, as well as humanantibodies and antibody fragments. Alternatively, a potential antagonistmay be a closely related protein, for example, a mutated form of theIL-22 polypeptide that recognizes the receptor but imparts no effect,thereby competitively inhibiting the action of the IL-22 polypeptide.

Another potential IL-22 polypeptide antagonist is an antisense RNA orDNA construct prepared using antisense technology, where, e.g., anantisense RNA or DNA molecule acts to block directly the translation ofmRNA by hybridizing to targeted mRNA and preventing protein translation.Antisense technology can be used to control gene expression throughtriple-helix formation or antisense DNA or RNA, both of which methodsare based on binding of a polynucleotide to DNA or RNA. For example, the5′ coding portion of the polynucleotide sequence, which encodes themature IL-22 polypeptides herein, is used to design an antisense RNAoligonucleotide of from about 10 to 40 base pairs in length. A DNAoligonucleotide is designed to be coinplementary to a region of the geneinvolved in transcription (triple helix—see Lee et al., Nucl. AcidsRes., 6:3073 (1979); Cooney et al., Science, 241: 456 (1988); Dervan etal., Science, 251:1360 (1991)), thereby preventing transcription and theproduction of the IL-22 polypeptide. The antisense RNA oligonucleotidehybridizes to the mRNA in vivo and blocks translation of the mRNAmolecule into the IL-22 polypeptide (antisense—Okano, Neurochem., 56:560(1991); Oligodeoxynucleotides as Antisense Inhibitors of Gene Expression(CRC Press: Boca Raton, Fla., 1988). The oligonucleotides describedabove can also be delivered to cells such that the antisense RNA or DNAmay be expressed in vivo to inhibit production of the IL-22 polypeptide.When antisense DNA is used, oligodeoxyribonucleotides derived from thetranslation-initiation site, e.g., between about −10 and +10 positionsof the target gene nucleotide sequence, are preferred.

Potential antagonists include small molecules that bind to the activesite, the receptor binding site, or growth factor or other relevantbinding site of the IL-22 polypeptide, thereby blocking the normalbiological activity of the IL-22 polypeptide. Examples of smallmolecules include, but are not limited to, small peptides orpeptide-like molecules, preferably soluble peptides, and syntheticnon-peptidyl organic or inorganic compounds.

Ribozymes are enzymatic RNA molecules capable of catalyzing the specificcleavage of RNA. Ribozymes act by sequence-specific hybridization to thecomplementary target RNA, followed by endonucleolytic cleavage. Specificribozyme cleavage sites within a potential RNA target can be identifiedby known techniques. For further details see, e.g., Rossi, CurrentBiology, 4:469–471 (1994), and PCT publication No. WO 97/33551(published Sep. 18, 1997).

Nucleic acid molecules in triple-helix formation used to inhibittranscription should be single-stranded and composed ofdeoxynucleotides. The base composition of these oligonucleotides isdesigned such that it promotes triple-helix formation via Hoogsteenbase-pairing rules, which generally require sizeable stretches ofpurines or pyrimidines on one strand of a duplex. For further detailssee, e.g., PCT publication No. WO 97/33551,supra.

These small molecules can be identified by any one or more of thescreening assays discussed hereinabove and/or by any other screeningtechniques well known for those skilled in the art.

Diagnostic and therapeutic uses of the herein disclosed molecules mayalso be based upon the positive functional assay hits disclosed anddescribed below.

F. Anti IL-22 Antibodies

The present invention further provides anti-IL-22 antibodies. Exemplaryantibodies include polyclonal, monoclonal, humanized, bispecific, andheteroconjugate antibodies.

1. Polyclonal Antibodies

The anti-IL-22 antibodies may comprise polyclonal antibodies. Methods ofpreparing polyclonal antibodies are known to the skilled artisan.Polyclonal antibodies can be raised in a mammal, for example, by one ormore injections of an immunizing agent and, if desired, an adjuvant.Typically, the immunizing agent and/or adjuvant will be injected in themammal by multiple subcutaneous or intraperitoneal injections. Theimmunizing agent may include the IL-22 polypeptide or a fusion proteinthereof. It may be useful to conjugate the immunizing agent to a proteinknown to be immunogenic in the mammal being immunized. Examples of suchimmunogenic proteins include but are not limited to keyhole limpethemocyanin, serum albumin, bovine thyroglobulin, and soybean trypsininhibitor. Examples of adjuvants which may be employed include Freund'scomplete adjuvant and MPL-TDM adjuvant (monophosphoryl Lipid A,synthetic trehalose dicorynomycolate). The immunization protocol may beselected by one skilled in the art without undue experimentation.

2. Monoclonal Antibodies

The anti-IL-22 antibodies may, alternatively, be monoclonal antibodies.Monoclonal antibodies may be prepared using hybridoma methods, such asthose described by Kohler and Milstein, Nature, 256:495 (1975). In ahybridoma method, a mouse, hamster, or other appropriate host animal, istypically immunized with an immunizing agent to elicit lymphocytes thatproduce or are capable of producing antibodies that will specificallybind to the immunizing agent. Alternatively, the lymphocytes may beimmunized in vitro.

The immunizing agent will typically include the IL-22 polypeptide or afusion protein thereof. Generally, either peripheral blood lymphocytes(“PBLs”) are used if cells of human origin are desired, or spleen cellsor lymph node cells are used if non-human mammalian sources are desired.The lymphocytes are then fused with an immortalized cell line using asuitable fusing agent, such as polyethylene glycol, to form a hybridomacell [Goding, Monoclonal Antibodies: Principles and Practice, AcademicPress, (1986) pp. 59–103]. Immortalized cell lines are usuallytransformed mammalian cells, particularly myeloma cells of rodent,bovine and human origin. Usually, rat or mouse myeloma cell lines areemployed. The hybridoma cells may be cultured in a suitable culturemedium that preferably contains one or more substances that inhibit thegrowth or survival of the unfused, immortalized cells. For example, ifthe parental cells lack the enzyme hypoxanthine guanine phosphoribosyltransferase (HGPRT or HPRT), the culture medium for the hybridomastypically will include hypoxanthine, aminopterin, and thymidine (“HATmedium”), which substances prevent the growth of HGPRT-deficient cells.

Preferred immortalized cell lines are those that fuse efficiently,support stable high level expression of antibody by the selectedantibody-producing cells, and are sensitive to a medium such as HATmedium. More preferred immortalized cell lines are murine myeloma lines,which can be obtained, for instance, from the Salk Institute CellDistribution Center, San Diego, Calif. and the American Type CultureCollection, Manassas, Va. Human myeloma and mouse-human heteromyelomacell lines also have been described for the production of humanmonoclonal antibodies [Kozbor, J. Immunol., 133:3001 (1984); Brodeur etal., Monoclonal Antibody Production Techniques and Applications, MarcelDekker, Inc., New York, (1987) pp. 51–63].

The culture medium in which the hybridoma cells are cultured can then beassayed for the presence of monoclonal antibodiesdirected against IL-22.Preferably, the binding specificity of monoclonal antibodies produced bythe hybridoma cells is determined by immunoprecipitation or by an invitro binding assay, such as radioimmunoassay (RIA) or enzyme-linkedimmunoabsorbent assay (ELISA). Such techniques and assays are known inthe art. The binding affinity of the monoclonal antibody can, forexample, be determined by the Scatchard analysis of Munson and Pollard,Anal. Biochem., 107:220 (1980).

After the desired hybridoma cells are identified, the clones may besubcloned by limiting dilution procedures and grown by standard methods[Goding, supra]. Suitable culture media for this purpose include, forexample, Dulbecco's Modified Eagle's Medium and RPMI-1640 medium.Alternatively, the hybridoma cells may be grown in vivo as ascites in amammal.

The monoclonal antibodies secreted by the subclones may be isolated orpurified from the culture medium or ascites fluid by conventionalimmunoglobulin purification procedures such as, for example, proteinA-Sepharose, hydroxylapatite chromatography, gel electrophoresis,dialysis, or affinity chromatography.

The monoclonal antibodies may also be made by recombinant DNA methods,such as those described in U.S. Pat. No. 4,816,567. DNA encoding themonoclonal antibodies of the invention can be readily isolated andsequenced using conventional procedures (e.g., by using oligonucleotideprobes that are capable of binding specifically to genes encoding theheavy and light chains of murine antibodies). The hybridoma cells of theinvention serve as a preferred source of such DNA. Once isolated, theDNA may be placed into expression vectors, which are then transfectedinto host cells such as simian COS cells, Chinese hamster ovary (CHO)cells, or myeloma cells that do not otherwise produce immunoglobulinprotein, to obtain the synthesis of monoclonal antibodies in therecombinant host cells. The DNA also may be modified, for example, bysubstituting the coding sequence for human heavy and light chainconstant domains in place of the homologous murine sequences [U.S. Pat.No. 4,816,567; Morrison et al., supra] or by covalently joining to theimmunoglobulin coding sequence all or part of the coding sequence for anon-immunoglobulin polypeptide. Such a non-immunoglobulin polypeptidecan be substituted for the constant domains of an antibody of theinvention, or can be substituted for the variable domains of oneantigen-combining site of an antibody of the invention to create achimeric bivalent antibody.

The antibodies may be monovalent antibodies. Methods for preparingmonovalent antibodies are well known in the art. For example, one methodinvolves recombinant expression of immunoglobulin light chain andmodified heavy chain. The heavy chain is truncated generally at anypoint in the Fe region so as to prevent heavy chain crosslinking.Alternatively, the relevant cysteine residues are substituted withanother amino acid residue or are deleted so as to prevent crosslinking.

In vitro methods are also suitable for preparing monovalent antibodies.Digestion of antibodies to produce fragments thereof, particularly, Fabfragments, can be accomplished using routine techniques known in theart.

3. Human and Humanized Antibodies

The anti-IL-22 antibodies of the invention may further comprisehumanized antibodies or human antibodies. Humanized forms of non-human(e.g., murine) antibodies are chimeric immunoglobulins, immunoglobulinchains or fragments thereof (such as Fv, Fab, Fab′, F(ab′)₂ or otherantigen-binding subsequences of antibodies) which contain minimalsequence derived from non-human immunoglobulin. Humanized antibodiesinclude human immunoglobulins (recipient antibody) in which residuesfrom a complementary determining region (CDR) of the recipient arereplaced by residues from a CDR of a non-human species (donor antibody)such as mouse, rat or rabbit having the desired specificity, affinityand capacity. In some instances, Fv framework residues of the humanimmunoglobulin are replaced by corresponding non-human residues.Humanized antibodies may also comprise residues which are found neitherin the recipient antibody nor in the imported CDR or frameworksequences. In general, the humanized antibody will comprisesubstantially all of at least one, and typically two, variable domains,in which all or substantially all of the CDR regions correspond to thoseof a non-human immunoglobulin and all or substantially all of the FRregions are those of a human immunoglobulin consensus sequence. Thehumanized antibody optimally also will comprise at least a portion of animmunoglobulin constant region (Fc), typically that of a humanimmunoglobulin [Jones et al., Nature, 321:522–525 (1986); Riechmann etal., Nature, 332:323–329 (1988); and Presta, Curr. Op. Struct. Biol.,2:593–596 (1992)].

Methods for humanizing non-human antibodies are well known in the art.Generally, a humanized antibody has one or more amino acid residuesintroduced into it from a source which is non-human. These non-humanamino acid residues are often referred to as “import” residues, whichare typically taken from an “import” variable domain. Humanization canbe essentially performed following the method of Winter and co-workers[Jones et al., Nature, 321:522–525 (1986); Riechmann et al., Nature,332:323–327 (1988); Verhoeyen et al., Science, 239: 1534–1536 (1988)],by substituting rodent CDRs or CDR sequences for the correspondingsequences of a human antibody. Accordingly, such “humanized” antibodiesare chimeric antibodies (U.S. Pat. No. 4,816,567), wherein substantiallyless than an intact human variable domain has been substituted by thecorresponding sequence from a non-human species. In practice, humanizedantibodies are typically human antibodies in which some CDR residues andpossibly some FR residues are substituted by residues from analogoussites in rodent antibodies.

Human antibodies can also be produced using various techniques known inthe art, including phage display libraries [Hoogenboom and Winter, J.Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol., 222:581(1991)]. The techniques of Cole et al. and Boerner et al. are alsoavailable for the preparation of human monoclonal antibodies (Cole etal., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77(1985) and Boerner et al., J. Immunol., 147(1):86–95 (1991)]. Similarly,human antibodies can be made by introducing of human immunoglobulin lociinto transgenic animals, e.g., mice in which the endogenousimmunoglobulin genes have been partially or completely inactivated. Uponchallenge, human antibody production is observed, which closelyresembles that seen in humans in all respects, including generearrangement, assembly, and antibody repertoire. This approach isdescribed, for example, in U.S. Pat. Nos. 5,545,807; 5,545,806;5,569,825; 5,625,126; 5,633,425; 5,661,016, and in the followingscientific publications: Marks et al., Bio/Technology 10, 779–783(1992); Lonberg et al., Nature 368 856–859 (1994); Morrison, Nature 368,812–13 (1994); Fishwild et al., Nature Biotechnology 14, 845–51 (1996);Neuberger, Nature Biotechnology 14, 826 (1996); Lonberg and Huszar,Intern. Rev. Immunol. 13 65–93 (1995).

The antibodies may also be affinity matured using known selection and/ormutagenesis methods as described above. Preferred affinity maturedantibodies have an affinity which is five times, more preferably 10times, even more preferably 20 or 30 times greater than the startingantibody (generally murine, humanized or human) from which the maturedantibody is prepared.

4. Bispecific Antibodies

Bispecific antibodies are monoclonal, preferably human or humanized,antibodies that have binding specificities for at least two differentantigens. In the present case, one of the binding specificities is forthe IL-22, the other one is for any other antigen, and preferably for acell-surface protein or receptor or receptor subunit.

Methods for making bispecific antibodies are known in the art.Traditionally, the recombinant production of bispecific antibodies isbased on the co-expression of two immunoglobulin heavy-chain/light-chainpairs, where the two heavy chains have different specificities [Milsteinand Cuello, Nature, 305:537–539 (1983)]. Because of the randomassortment of immunoglobulin heavy and light chains, these hybridomas(quadromas) produce a potential mixture of ten different antibodymolecules, of which only one has the correct bispecific structure. Thepurification of the correct molecule is usually accomplished by affinitychromatography steps. Similar procedures are disclosed in WO 93/08829,published 13 May 1993, and in Traunecker et al., EMBO J., 10:3655–3659(1991).

Antibody variable domains with the desired binding specificities(antibody-antigen combining sites) can be fused to immunoglobulinconstant domain sequences. The fusion preferably is with animmunoglobulin heavy-chain constant domain, comprising at least part ofthe hinge, CH2, and CH3 regions. It is preferred to have the firstheavy-chain constant region (CH1) containing the site necessary forlight-chain binding present in at least one of the fusions. DNAsencoding the immunoglobulin heavy-chain fusions and, if desired, theimmunoglobulin light chain, are inserted into separate expressionvectors, and are co-transfected into a suitable host organism. Forfurther details of generating bispecific antibodies see, for example,Suresh et al., Methods in Enzymology, 121:210 (1986).

According to another approach described in WO 96/27011, the interfacebetween a pair of antibody molecules can be engineered to maximize thepercentage of heterodimers which are recovered from recombinant cellculture. The preferred interface comprises at least a part of the CH3region of an antibody constant domain. In this method, one or more smallamino acid side chains from the interface of the first antibody moleculeare replaced with larger side chains (e.g. tyrosine or tryptophan).Compensatory “cavities” of identical or similar size to the large sidechain(s) are created on the interface of the second antibody molecule byreplacing large amino acid side chains with smaller ones (e.g. alanineor threonine). This provides a mechanism for increasing the yield of theheterodimer over other unwanted end-products such as homodimers.

Bispecific antibodies can be prepared as full length antibodies orantibody fragments (e.g. F(ab′)₂ bispecific antibodies). Techniques forgenerating bispecific antibodies from antibody fragments have beendescribed in the literature. For example, bispecific antibodies can beprepared can be prepared using chemical linkage. Brennan et al., Science229:81 (1985) describe a procedure wherein intact antibodies areproteolytically cleaved to generate F(ab′)₂ fragments. These fragmentsare reduced in the presence of the dithiol complexing agent sodiumarsenite to stabilize vicinal dithiols and prevent intermoleculardisulfide formation. The Fab′ fragments generated are then converted tothionitrobenzoate (TNB) derivatives. One of the Fab′-TNB derivatives isthen reconverted to the Fab′-thiol by reduction with mercaptoethylamineand is mixed with an equimolar amount of the other Fab′-TNB derivativeto form the bispecific antibody. The bispecific antibodies produced canbe used as agents for the selective immobilization of enzymes.

Fab′ fragments may be directly recovered from E. coli and chemicallycoupled to form bispecific antibodies. Shalaby et al., J. Exp. Med.175:217–225 (1992) describe the production of a fully humanizedbispecific antibody F(ab′)₂ molecule. Each Fab′ fragment was separatelysecreted from E. coli and subjected to directed chemical coupling invitro to form the bispecific antibody. The bispecific antibody thusformed was able to bind to cells overexpressing the ErbB2 receptor andnormal human T cells, as well as trigger the lytic activity of humancytotoxic lymphocytes against human breast tumor targets.

Various technique for making and isolating bispecific antibody fragmentsdirectly from recombinant cell culture have also been described. Forexample, bispecific antibodies have been produced using leucine zippers.Kostelny et al., J. Immunol. 148(5):1547–1553 (1992). The leucine zipperpeptides from the Fos and Jun proteins were linked to the Fab′ portionsof two different antibodies by gene fusion. The antibody homodimers werereduced at the hinge region to form monomers and then re-oxidized toform the antibody heterodimers. This method can also be utilized for theproduction of antibody homodimers. The “diabody” technology described byHollinger et al., Proc. Natl. Acad. Sci. USA 90:6444–6448 (1993) hasprovided an alternative mechanism for making bispecific antibodyfragments. The fragments comprise a heavy-chain variable domain (V_(H))connected to a light-chain variable domain (V_(L)) by a linker which istoo short to allow pairing between the two domains on the same chain.Accordingly, the V_(H) and V_(L) domains of one fragment are forced topair with the complementary V_(L) and V_(H) domains of another fragment,thereby forming two antigen-binding sites. Another strategy for makingbispecific antibody fragments by the use of single-chain Fv (sFv) dimershas also been reported. See, Gruber et al., J. Immunol. 152:5368 (1994).

Antibodies with more than two valencies are contemplated. For example,trispecific antibodies can be prepared. Tutt et al., J. Immunol. 147:60(1991).

Exemplary bispecific antibodies may bind to two different epitopes on agiven IL-22 polypeptide herein. Alternatively, an anti-IL-22 polypeptidearm may be combined with an arm which binds to a triggering molecule ona leukocyte such as a T-cell receptor molecule (e.g. CD2, CD3, CD28, orB7), or Fc receptors for IgG (FcγR), such as FcγRI (CD64), FcγRII (CD32)and FcγRIII (CD16) so as to focus cellular defense mechanisms to thecell expressing the particular IL-22 polypeptide. Bispecific antibodiesmay also be used to localize cytotoxic agents to cells which express aparticular IL-22 polypeptide. These antibodies possess a IL-22-bindingarm and an arm which binds a cytotoxic agent or a radionuclide chelator,such as EOTUBE, DPTA, DOTA, or TETA. Another bispecific antibody ofinterest binds the IL-22 polypeptide and further binds tissue factor(TF).

5. Heteroconjugate Antibodies

Heteroconjugate antibodies are also within the scope of the presentinvention. Heteroconjugate antibodies are composed of two covalentlyjoined antibodies. Such antibodies have, for example, been proposed totarget immune system cells to unwanted cells [U.S. Pat. No. 4,676,980],and for treatment of HIV infection [WO 91/00360; WO 92/200373; EP03089]. It is contemplated that the antibodies may be prepared in vitrousing known methods in synthetic protein chemistry, including thoseinvolving crosslinking agents. For example, immunotoxins may beconstructed using a disulfide exchange reaction or by forming athioether bond. Examples of suitable reagents for this purpose includeiminothiolate and methyl-4-mercaptobutyrimidate and those disclosed, forexample, in U.S. Pat. No. 4,676,980.

6. Effector Function Engineering

It may be desirable to modify the antibody of the invention with respectto effector function, so as to enhance, e.g., the effectiveness of theantibody in treating cancer. For example, cysteine residue(s) may beintroduced into the Fc region, thereby allowing interchain disulfidebond formation in this region. The homodimeric antibody thus generatedmay have improved internalization capability and/or increasedcomplement-mediated cell killing and antibody-dependent cellularcytotoxicity (ADCC). See Caron et al., J. Exp Med., 176: 1191–1195(1992) and Shopes, J. Immunol., 148: 2918–2922 (1992). Homodimericantibodies with enhanced anti-tumor activity may also be prepared usingheterobifunctional cross-linkers as described in Wolff et al. CancerResearch, 53: 2560–2565 (1993). Alternatively, an antibody can beengineered that has dual Fc regions and may thereby have enhancedcomplement lysis and ADCC capabilities. See Stevenson et al.,Anti-Cancer Drug Design, 3: 219–230 (1989).

7. Immunoconjugates

The invention also pertains to immunoconjugates comprising an antibodyconjugated to a cytotoxic agent such as a chemotherapeutic agent, toxin(e.g., an enzymatically active toxin of bacterial, fungal, plant, oranimal origin, or fragments thereof), or a radioactive isotope (i.e., aradioconjugate).

Chemotherapeutic agents useful in the generation of suchimmunoconjugates have been described above. Enzymatically active toxinsand fragments thereof that can be used include diphtheria A chain,nonbinding active fragments of diphtheria toxin, exotoxin A chain (fromPseudomonas aeruginosa), ricin A chain, abrin A chain, modeccin A chain,alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolacaamericana proteins (PAPI, PAPII, and PAP-S), momordica charantiainhibitor, curcin, crotin, sapaonaria officinalis inhibitor, gelonin,mitogellin, restrictocin, phenomycin, enomycin, and the tricothecenes. Avariety of radionuclides are available for the production ofradioconjugated antibodies. Examples include ²¹²Bi, ¹³¹I, ¹³¹In, ⁹⁰Y,and ¹⁸⁶Re. Conjugates of the antibody and cytotoxic agent are made usinga variety of bifunctional protein-coupling agents such asN-succinimidyl-3-(2-pyridyldithiol) propionate (SPDP), iminothiolane(IT), bifunctional derivatives of imidoesters (such as dimethyladipimidate HCL), active esters (such as disuccinimidyl suberate),aldehydes (such as glutareldehyde), bis-azido compounds (such as bis(p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (such asbis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astolyene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin canbe prepared as described in Vitetta et al., Science, 238: 1098 (1987).Carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent forconjugation of radionucleotide to the antibody. See WO94/11026.

In another embodiment, the antibody may be conjugated to a “receptor”(such streptavidin) for utilization in tumor pretargeting wherein theantibody-receptor conjugate is administered to the patient, followed byremoval of unbound conjugate from the circulation using a clearing agentand then administration of a “ligand” (e.g., avidin) that is conjugatedto a cytotoxic agent (e.g., a radionucleotide).

8. Immunoliposomes

The antibodies disclosed herein may also be formulated asimmunoliposomes. Liposomes containing the antibody are prepared bymethods known in the art, such as described in Epstein et al., Proc.Natl. Acad. Sci. USA, 82: 3688 (1985); Hwang et al., Proc. Natl. Acad.Sci. USA, 77: 4030 (1980); and U.S. Pat. Nos. 4,485,045 and 4,544,545.Liposomes with enhanced circulation time are disclosed in U.S. Pat. No.5,013,556.

Particularly useful liposomes can be generated by the reverse-phaseevaporation method with a lipid composition comprisingphosphatidylcholine, cholesterol, and PEG-derivatizedphosphatidylethanolamine (PEG-PE). Liposomes are extruded throughfilters of defined pore size to yield liposomes with the desireddiameter. Fab′ fragments of the antibody of the present invention can beconjugated to the liposomes as described in Martin et al J. Biol. Chem.,257: 286–288 (1982) via a disulfide-interchange reaction. Achemotherapeutic agent (such as Doxorubicin) is optionally containedwithin the liposome. See Gabizon et al., J. National Cancer Inst.,81(19): 1484 (1989).

9. Pharmaceutical Compositions of Antibodies

Antibodies specifically binding an IL-22 polypeptide identified herein,as well as other molecules identified by the screening assays disclosedhereinbefore, can be administered for the treatment of various disordersin the form of pharmaceutical compositions.

If the IL-22 polypeptide is intracellular and whole antibodies are usedas inhibitors, internalizing antibodies are preferred. However,lipofections or liposomes can also be used to deliver the antibody, oran antibody fragment, into cells. Where antibody fragments are used, thesmallest inhibitory fragment that specifically binds to the bindingdomain of the target protein is preferred. For example, based upon thevariable-region sequences of an antibody, peptide molecules can bedesigned that retain the ability to bind the target protein sequence.Such peptides can be synthesized chemically and/or produced byrecombinant DNA technology. See, e.g., Marasco et al., Proc. Natl. Acad.Sci. USA, 90: 7889–7893 (1993).

The formulation herein may also contain more than one active compound asnecessary for the particular indication being treated, preferably thosewith complementary activities that do not adversely affect each other.Alternatively, or in addition, the composition may comprise an agentthat enhances its function, such as, for example, acytotoxic agent,cytokine, chemotherapeutic agent, or growth-inhibitory agent. Suchmolecules are suitably present in combination in amounts that areeffective for the purpose intended.

The active ingredients may also be entrapped in microcapsules prepared,for example, by coacervation techniques or by interfacialpolymerization, for example, hydroxymethyl cellulose orgelatin-microcapsules and poly-(methylmethacylate) microcapsules,respectively, in colloidal drug delivery systems (for example,liposomes, albumin microspheres, microemulsions, nano-particles, andnanocapsules) or in macroemulsions. Such techniques are disclosed inRemington's Pharmaceutical Sciences, supra.

The formulations to be used for in vivo administration must be sterile.This is readily accomplished by filtration through sterile filtrationmembranes.

Sustained-release preparations may be prepared. Suitable examples ofsustained-release preparations include semipermeable matrices of solidhydrophobic polymers containing the antibody, which matrices are in theform of shaped articles, e.g., films, or microcapsules. Examples ofsustained-release matrices include polyesters, hydrogels (for example,poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides(U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and γethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradablelactic acid-glycolic acid copolymers such as the LUIL-22N DEPOT™(injectable microspheres composed of lactic acid-glycolic acid copolymerand leuprolide acetate), and poly-D-(−)-3-hydroxybutyric acid. Whilepolymers such as ethylene-vinyl acetate and lactic acid-glycolic acidenable release of molecules for over 100 days, certain hydrogels releaseproteins for shorter time periods. When encapsulated antibodies remainin the body for a long time, they may denature or aggregate as a resultof exposure to moisture at 37° C., resulting in a loss of biologicalactivity and possible changes in immunogenicity. Rational strategies canbe devised for stabilization depending on the mechanism involved. Forexample, if the aggregation mechanism is discovered to be intermolecularS—S bond formation through thio-disulfide interchange, stabilization maybe achieved by modifying sulfhydryl residues, lyophilizing from acidicsolutions, controlling moisture content, using appropriate additives,and developing specific polymer matrix compositions.

G. Uses for anti-IL-22 Antibodies

The anti-IL-22 antibodies of the invention have various utilities. Forexample, anti-IL-22 antibodies may be used in diagnostic assays forIL-22, e.g., detecting its expression (and in some cases, differentialexpression) in specific cells, tissues, or serum. Various diagnosticassay techniques known in the art may be used, such as competitivebinding assays, direct or indirect sandwich assays andimmunoprecipitation assays conducted in either heterogeneous orhomogeneous phases [Zola, Monoclonal Antibodies: A Manual of Techniques,CRC Press, Inc. (1987) pp. 147–158]. The antibodies used in thediagnostic assays can be labeled with a detectable moiety. Thedetectable moiety should be capable of producing, either directly orindirectly, a detectable signal. For example, the detectable moiety maybe a radioisotope, such as ³H, ¹⁴C, ³²P, ³⁵S, or ¹²⁵I, a fluorescent orchemiluiminescent compound, such as fluorescein isothiocyanate,rhodamine, or luciferin, or an enzyme, such as alkaline phosphatase,beta-galactosidase or horseradish peroxidase. Any method known in theart for conjugating the antibody to the detectable moiety may beemployed, including those methods described by Hunter et al., Nature,144:945 (1962); David et al., Biochemistry, 13:1014 (1974); Pain et al.,J. Immunol. Meth., 40:219 (1981); and Nygren, J. Histochem. andCytochem., 30:407 (1982).

Anti-IL-22 antibodies also are useful for the affinity purification ofIL-22 from recombinant cell culture or natural sources. In this process,the antibodies against IL-22 are immobilized on a suitable support, sucha Sephadex resin or filter paper, using methods well known in the art.The immobilized antibody then is contacted with a sample containing theIL-22 to be purified, and thereafter the support is washed with asuitable solvent that will remove substantially all the material in thesample except the IL-22, which is bound to the immobilized antibody.Finally, the support is washed with another suitable solvent that willrelease the IL-22 from the antibody. Anti-IL-22 antibodies also find usein binding to IL-22 and thereby inhibiting PAP1 expression, mayalleviate the severity of pancreatic disorders.

The following examples are offered for illustrative purposes only, andare not intended to limit the scope of the present invention in any way.

All patent and literature references cited in the present specificationare hereby incorporated by reference in their entirety.

EXAMPLES

Commercially available reagents referred to in the examples were usedaccording to manufacturer's instructions unless otherwise indicated. Thesource of those cells identified in the following examples, andthroughout the specification, by ATCC accession numbers is the AmericanType Culture Collection, Manassas, Va.

Example 1

Cloning of IL-22

Interleukin-22 (DNA125185-2806) was identified by applying a proprietarysignal sequence finding algorithm developed by Genentech, Inc. (SouthSan Francisco, Calif.) upon ESTs as well as clustered and assembled ESTfragments from public (e.g., GenBank) and/or private (LIFESEQ®, IncytePharmaceuticals, Inc., Palo Alto, Calif.) databases. The signal sequencealgorithm computes a secretion signal score based on the character ofthe DNA nucleotides surrounding the first and optionally the secondmethionine codon(s) (ATG) at the 5′-end of the sequence or sequencefragment under consideration. The nucleotides following the first ATGmust code for at least 35 unambiguous amino acids without any stopcodons. If the first ATG has the required amino acids, the second is notexamined. If neither meets the requirement, the candidate sequence isnot scored. In order to determine whether the EST sequence contains anauthentic signal sequence, the DNA and corresponding amino acidsequences surrounding the ATG codon are scored using a set of sevensensors (evaluation parameters) known to be associated with secretionsignals.

Use of the above described signal sequence algorithm allowedidentification of an EST cluster sequence from the Incyte database,designated herein as 5086173H1. This EST cluster sequence was thencompared to a variety of expressed sequence tag (EST) databases whichincluded public EST databases (e.g., GenBank) and a proprietary EST DNAdatabase (LIFESEQ®, Incyte Pharmaceuticals, Palo Alto, Calif.) toidentify existing homologies. The homology search was performed usingthe computer program BLAST or BLAST2 (Altshul et al., Methods inEnzymology 266:460–480 (1996)). Those comparisons resulting in a BLASTscore of 70 (or in some cases 90) or greater that did not encode knownproteins were clustered and assembled into a consensus DNA sequence withthe program “phrap” (Phil Green, University of Washington, Seattle,Wash.). The consensus sequence obtained therefrom is herein designatedDNA110880.

In light of an observed sequence homology between the DNA110880 sequenceand an EST sequence encompassed within clone no. 5088384 from the Incytedatabase, clone no. 5088384 was purchased and the cDNA insert wasobtained and sequenced. It was found herein that that cDNA insertencoded a full-length protein. The sequence of this cDNA insert is shownin FIG. 1 and is herein designated as IL-22 (DNA 125185-2806).

Clone DNA 125185-2806 contains a single open reading frame with anapparent translational initiation site at nucleotide positions 58–60 andending at the stop codon at nucleotide positions 595–597 (FIG. 1, SEQ IDNO 1). The predicted polypeptide precursor is 179 amino acids long (FIG.2, SEQ ID NO: 2). The full-length IL-22 protein shown in FIG. 2 has anestimated molecular weight of about 20,011 daltons and a pI of about8.10. Analysis of the full-length IL-22 sequence shown in FIG. 2 (SEQ IDNO:2) evidences the presence of a variety of important polypeptidedomains as shown in FIG. 2, wherein the locations given for thoseimportant polypeptide domains are approximate as described above. IL-22(DNA 125185-2806) has been deposited with ATCC on Dec. 7, 1999 and isassigned ATCC deposit No. PTA-1031.

Example 2

Identification of Receptor/Ligand Interactions

In this assay, various IL-22 polypeptides are tested for ability to bindto a panel of potential receptor or ligand molecules for the purpose ofidentifying receptor/ligand interactions. The identification of a ligandfor a known receptor, a receptor for a known ligand or a novelreceptor/ligand pair is useful for a variety of indications including,for example, targeting bioactive molecules (linked to the ligand orreceptor) to a cell known to express the receptor or ligand, use of thereceptor or ligand as a reagent to detect the presence of the ligand orreceptor in a composition suspected of containing the same, wherein thecomposition may comprise cells suspected of expressing the ligand orreceptor, modulating the growth of or another biological orimmunological activity of a cell known to express or respond to thereceptor or ligand, modulating the immune response of cells or towardcells that express the receptor or ligand, allowing the preparation ofagonists, antagonists and/or antibodies directed against the receptor orligand which will modulate the growth of or a biological orimmunological activity of a cell expressing the receptor or ligand, andvarious other indications which will be readily apparent to theordinarily skilled artisan.

The assay is performed as follows. An IL-22 polypeptide of the presentinvention suspected of being a ligand for a receptor is expressed as afusion protein containing the Fc domain of human IgG (an immunoadhesin).Receptor-ligand binding is detected by allowing interaction of theimmunoadhesin polypeptide with cells (e.g. Cos cells) expressingcandidate IL-22 polypeptide receptors and visualization of boundimmunoadhesin with fluorescent reagents directed toward the Fc fusiondomain and examination by microscope. Cells expressing candidatereceptors are produced by transient transfection, in parallel, ofdefined subsets of a library of cDNA expression vectors encoding IL-22polypeptides that may function as receptor molecules. Cells are thenincubated for 1 hour in the presence of the IL-22 polypeptideimmunoadhesin being tested for possible receptor binding. The cells arethen washed and fixed with paraformaldehyde. The cells are thenincubated with fluorescent conjugated antibody directed against the Fcportion of the IL-22 polypeptide immunoadhesin (e.g. FITC conjugatedgoat anti-human-Fc antibody). The cells are then washed again andexamined by microscope. A positive interaction is judged by the presenceof fluorescent labeling of cells transfected with cDNA encoding aparticular IL-22 polypeptide receptor or pool of receptors and anabsence of similar fluorescent labeling of similarly prepared cells thathave been transfected with other cDNA or pools of cDNA. If a definedpool of cDNA expression vectors is judged to be positive for interactionwith a IL-22 polypeptide immunoadhesin, the individual cDNA species thatcomprise the pool are tested individually (the pool is “broken down”) todetermine the specific cDNA that encodes a receptor able to interactwith the IL-22 polypeptide immunoadhesin.

In another embodiment of this assay, an epitope-tagged potential ligandIL-22 polypeptide (e.g. 8 histidine “His” tag) is allowed to interactwith a panel of potential receptor IL-22 polypeptide molecules that havebeen expressed as fusions with the Fc domain of human IgG(immunoadhesins). Following a 1 hour co-incubation with the epitopetagged IL-22 polypeptide, the candidate receptors are eachimmunoprecipitated with protein A beads and the beads are washed.Potential ligand interaction is determined by western blot analysis ofthe immunoprecipitated complexes with antibody directed towards theepitope tag. An interaction is judged to occur if a band of theanticipated molecular weight of the epitope tagged protein is observedin the western blot analysis with a candidate receptor, but is notobserved to occur with the other members of the panel of potentialreceptors.

Using these assays, the following receptor/ligand interactions have beenherein identified:

-   1. IL-22 binds to IL-10Rβ. FIG. 10 (SEQ ID NO: 3)-   2. IL-22 binds to IL-22R FIG. 11 (SEQ ID NO: 4)    (See also [Xie et al., J. Biol. Chem (2000) 275, 31335–31339])

Example 3

Expression of IL-22 Receptor in Multiple Human Tissues

Multiple tissue Northern Blots were obtained from Clontech (Palo Alto,Calif.). These blots were hybridized with a probe made by end labeling a50-mer IL-22 receptor specific oligonucleotide using ³²P-γATP and T4polynucleotide kinase. Blots were washed 3× with 2×SSC/0.2%SDS and 1×with 0.2×SSC/0.1% SDA at 42 C. The blots were then exposed to X-OMATfilm with intensifying screens for 16 hours. The result is shown in FIG.3. This shows that IL-22 receptor is expressed highly in pancreas, withlower level of IL-22 receptor observed in small intestine, liver, kidneyand colon.

Example 4

Tagman™ Analysis

Total RNA was obtained by homogenizing tissues in lysis buffer andlayering the lysate over cesium chloride (5.7 M CsCl/50 mM EDTA.) andcentrifugation at 35,000×g for 16 hours. The cell pellets were thenresuspended in RNAse free water. 50 nanograms of RNA was then used toperform Taqman™ analysis. The value of expression was set relative to ahousekeeping gene GAPDH.

The TaqMan™ reaction is a fluorescent PCR-based technique which makesuse of the 5′ exonuclease activity of Taq DNA polymerase enzyme tomonitor amplification in real time. Two oligonucleotide primers are usedto generate an amplicon typical of a PCR reaction. A thirdoligonucleotide, or probe, is designed to detect nucleotide sequencelocated between the two PCR primers. The probe is non-extendible by TaqDNA polymerase enzyme, and is labeled with a reporter fluorescent dyeand a quencher fluorescent dye. Any laser-induced emission from thereporter dye is quenched by the quenching dye when the two dyes arelocated close together as they are on the probe. During theamplification reaction, the Taq DNA polymerase enzyme cleaves the probein a template-dependent manner. The resultant probe fragmentsdisassociate in solution, and signal from the released reporter dye isfree from the quenching effect of the second fluorophore. One moleculeof reporter dye is liberated for each new molecule synthesized, anddetection of the unquenched reporter dye provides the basis forquantitative interpretation of the data.

The results of the TaqMan™ reaction are reported in delta (Δ) Ct units.TaqMan™ assay data are initially expressed as Ct, or the thresholdcycle. This is defined as the cycle at which the reporter signalaccumulates above the background level of fluorescence. The ΔCt valuesare used as quantitative measurement of the relative number of startingcopies of a particular target sequence in a nucleic acid sample whencomparing cancer results to normal human results. One unit correspondsto 1 PCR cycle or approximately a 2-fold amplification relative tonormal, two units corresponds to 4-fold, 3 units to 8-fold amplificationand soon. Quantitation was obtained using primers and a TaqMan™fluorescent probe derived from the IL-22 receptor (IL-22R) encodinggene. Regions of IL-22R which are most likely to contain unique nucleicacid sequences and which are least likely to have spliced out intronsare preferred for the primer and probe derivation, e.g., 3′-untranslatedregions. The sequences for the primers and probes (forward, reverse andprobe) used for the IL-22R gene amplification analysis were as follows:

165608.tm.f1(forward primer) 5′TGCAACCTGACGGTGGAGA 3′ (SEQ ID NO: 5)165608.tm.r1(reverse primer) 5′AGAGAGCTGAACCTGTCAGTCATCTT 3′ (SEQ ID NO:6) 165608.tm.p1(probe) 5′ CAGTGCGGGAGGCCGGTCA 3′ (SEQ ID NO: 7)

The TaqMan™ procedure is run on a real-time quantitative PCR device suchas the ABI Prism 7700TM. The system consists of a thermocycler, laser,charge-coupled device (CCD) camera and computer. The system amplifiessamples in a 96-well format on a thermocycler. During amplification,laser-induced fluorescent signal is collected in real-time through fiberoptics cables for all 96 wells, and detected at the CCD. The systemincludes software for running the instrument and for analyzing the data.

The fluorometricly determined concentration of mRNA was then used todilute each sample to 10 ng/μl in ddH₂O. This was done simultaneously onall template samples for a single TaqMan™ plate assay, and with enoughmaterial to run several assays. The samples were tested in triplicatewith Taqman™ primers and probe both B-actin and GAPDH on a single platewith normal human mRNA, no Reverse Transcriptase added and no-templatecontrols. The reverse transcriptase used was SuperScript II (LifeTechnologies Inc., Grand Island, N.Y.). The Taq Polymerase, Buffers, anddNTPs were supplied by Perkin Elmer (Perkin Elmer, Applied BiosystemsDivision, Foster City, Calif. The thermocycler conditions were asfollows.

a.  1 cycle of: Reverse transcription 48° C., 30 minutes b.  1 cycle of:Denature 95° C., 10 minutes c. 40 cycles of: Denature 95° C., 30 secondsExtend 60° C., 90 seconds Results: The results of this are shown in FIG.4. Interleukin-22 receptor was expressed highest in pancreas, withexpression detected in fetal liver, adult liver, kidney, intestine andcolon.

Example 5

STAT Activation in Pancreatic Acinar Cells

266-6 is a cell line derived from mouse pancreatic acinar cells and wasobtained from ATCC (ATCC deposit No. CRL-2151). These cells werecultured in DMEM supplemented with 10% FBS penicillin/streptomycin and 2mM L-glutamine (Life Technologies Gaithersburg, Md.) and maintained in5% CO² humidified chamber. 266-6 cells were stimulated with control ofhis-tagged mouse IL-22 containing baculovirus supernatant (10% vol/vol)for 10 minutes at 37° C. Cell lysates were prepared and gel shift assayswere performed. Antibodies used for STAT supershift experiments werepurchased from Santa Cruz Biotechnology (Santa Cruz, Calif.). STATbinding proteins induced by murine IL-22 could be supershifted withantibodies to STAT 3, as shown in FIG. 5. This demonstrates that thepancreatic acinar cell line 266-6 responds to murine IL-22 by activationof the Janus Kinase (JAK-STAT) pathway, and through STAT3 specifically.The pancreatic beta cell line (NIT-1), does not utilize the JAK-STATpathway (data not shown).

Example 6

IL-22 Increases Expression of Pancreatitis Associated Protein (PAP1)

Pancreatitis Associated Protein (PAP1) is a secreted protein and isoverexpressed in acute pancreatitis, with expression levels almostcompletely absent in normal pancreas [Iovanna et al., J. Biol.Chem.(1991), 266, 24664–24669]. The exact function of PAP1 is unknown,although it is structurally related to the carbohydrate recognitiondomain of c-type lectins and is a member of the REG family of molecules.Reports have suggested trophic activities for members of the REG family[Nishimune et al., (2000) Nat Cell Biol 2(12), 906-14]. Induction ofPAP1 with other cytokines have such as IL-1 or IL-6 either alone or incombination failed to upregulate PAP1 [Dusetti et al., (1995) J. BiolChem 270, 22417–22421]. Increased serum levels of PAP1 is seen inpatients with Celiac disease, [Carroccio et al., (1997) Digestion 58,98–103] a small bowel disorder, and in patients with cystic fibrosis[Iovanna et al., (1994) C.R. Acad. Sci 317,561–564].

266-6 cells were treated with purified his-tagged murine IL-22 for 6hours. Total RNA was extracted by homogenizing cells in lysis buffer andlayering the cell lysates of cesium chloride (5.7 M CsCl/50 mM EDTA ).The cell lysates were centrifuged at 35,000×g for 16 hours. The cellpellets were resuspended in RNAse free water. 20 microgram of RNA wasresolved using a formaldehyde denaturing gel and transferred on tonitrocellulose membranes. Hybridization was performed using aPAP1-specific ³²P-γATP labeled oligonuclotide probe. Blots were washed3× with 2×SSC/0.2% SDS and 1× with 0.2×SSC/0.1% SDS at 42° C. Blots wereexposed to X-OMAT film with intensifying screens for 16 hours. The blotswere then stripped and reprobed using a ³²P-γATP labeled GAPDH specificoligonucleotide probe. This result is shown in FIG. 6A. Incubation ofthe 266-6 cells with murine IL-22 resulted in dramatic induction of PAP1gene expression. To determine if primary pancreatic acinar cells arealso able to respond to murine IL-22, primary acinar cells were isolatedfrom mouse pancreas by collagenase digestion and incubated for 6 hourswith or without purified murine IL-22. RNA was prepared as above andPAP1 expression was examined. As with the 266-6 cell line, murine IL-22induced substantial upregulation of PAP1 expression in the isolatedprimary pancreatic acinar cells.

Example 7

IL-22 Induces PAP1 Gene Expression in vivo

In order to examine the effects of murine IL-22 in vivo, three groups ofmice were injected intraperitoneally with 25 micrograms murine IL-22 orPBS. The mice were harvested at 2, 6 or 24 hours following injection,and their pancreas removed and quick frozen. RNA from this tissue wasprepared and Northern Blotting analysis as described in Example 5 wasperformed using a PAP1 gene specific probe. As shown in FIG. 7, PAP1 wasupregulated within 2 hours of murine IL-22 injection, reaching a peakexpression at about 6 hours, and was still induced at 24 hours.

Example 8

IL-22 Pancreatic Response

To confirm that the observed pancreas response was due to IL-22 receptormediated signaling rather than a non-specific toxicity of therecombinant protein, mIL-22 was injected into IL-10Rβ (−/−) deficientmice. These mice lack one functional chain of the IL-10Rβ/IL-22R complexfor IL-22 signaling. IL-10Rβ deficient mice were previously reported tolack responsiveness to IL-10. Splenic monocytes isolated from IL-10Rβdeficient mice do not exhibit IL-10 mediated inhibition oflipopolysaccharide (LPS) induced IL-6 secretion (FIG. 8) or TNF-alpha(not shown). As had been noted previously, IL-22 does not appear toeffect monocyte response to LPS (Xie et al., (2000) J. Biol. Chem., 275,31335–31339). IL-22 does not appear to effect monocyte response to LPS.

Example 9

IL-22 Response in IL-10Rβ Deficient Mice.

Mice that are deficient or “knocked out” for IL-10Rβ, lack onefunctional chain of the IL-22R/IL-10Rβ receptor complex necessary forIL-22 signaling, and IL-10Rβ deficient mice were previously reported tolack IL-10 responsiveness. IL-10Rβ deficient mice and wild type micewere injected intraperitoneally with or without murine IL-22 andharvested 16 hours post injection and Northern Blot analysis performedon pancreatic RNA using PAP1 probes as previously described. As theIL-10Rβ mice lack one of the chains necessary to transduce anintracellular signal, no induction of PAP1 was evident shown in FIG. 9.In contrast, wild type mice showed a strong induction of PAP1 expressionalso shown in FIG. 9.

Example 10

Use of IL-22 as a Hybridization Probe

The following method describes use of a nucleotide sequence encodingIL-22 as a hybridization probe.

DNA comprising the coding sequence of full-length or mature IL-22 asdisclosed herein is employed as a probe to screen for homologous DNAs(such as those encoding naturally-occurring variants of IL-22) in humantissue cDNA libraries or human tissue genomic libraries.

Hybridization and washing of filters containing either library DNAs isperformed under the following high stringency conditions. Hybridizationof radiolabeled IL-22-derived probe to the filters is performed in asolution of 50% formamide, 5×SSC, 0.1% SDS, 0.1% sodium pyrophosphate,50 mM sodium phosphate, pH 6.8, 2× Denhardt's solution, and 10% dextransulfate at 42° C. for 20 hours. Washing of the filters is performed inan aqueous solution of 0.1×SSC and 0.1% SDS at 42° C.

DNAs having a desired sequence identity with the DNA encodingfull-length native sequence IL-22 can then be identified using standardtechniques known in the art.

Example 11

Expression of IL-22 in E. coli

This example illustrates preparation of an unglycosylated form of IL-22by recombinant expression in E. coli.

The DNA sequence encoding IL-22 is initially amplified using selectedPCR primers. The primers should contain restriction enzyme sites whichcorrespond to the restriction enzyme sites on the selected expressionvector. A variety of expression vectors may be employed. An example of asuitable vector is pBR322 (derived from E. coli; see Bolivar et al.,Gene, 2:95 (1977)) which contains genes for ampicillin and tetracyclineresistance. The vector is digested with restriction enzyme anddephosphorylated. The PCR amplified sequences are then ligated into thevector. The vector will preferably include sequences which encode for anantibiotic resistance gene, a trp promoter, a polyhis leader (includingthe first six STII codons, polyhis sequence, and enterokinase cleavagesite), the IL-22 coding region, lambda transcriptional terminator, andan argU gene.

The ligation mixture is then used to transform a selected E. coli strainusing the methods described in Sambrook et al., supra. Transformants areidentified by their ability to grow on LB plates and antibioticresistant colonies are then selected. Plasmid DNA can be isolated andconfirmed by restriction analysis and DNA sequencing.

Selected clones can be grown overnight in liquid culture medium such asLB broth supplemented with antibiotics. The overnight culture maysubsequently be used to inoculate a larger scale culture. The cells arethen grown to a desired optical density, during which the expressionpromoter is turned on.

After culturing the cells for several more hours, the cells can beharvested by centrifugation. The cell pellet obtained by thecentrifugation can be solubilized using various agents known in the art,and the solubilized IL-22 protein can then be purified using a metalchelating column under conditions that allow tight binding of theprotein.

IL-22 may be expressed in E. coli in a poly-His tagged form, using thefollowing procedure. The DNA encoding IL-22 is initially amplified usingselected PCR primers. The primers will contain restriction enzyme siteswhich correspond to the restriction enzyme sites on the selectedexpression vector, and other useful sequences providing for efficientand reliable translation initiation, rapid purification on a metalchelation column, and proteolytic removal with enterokinase. ThePCR-amplified, poly-His tagged sequences are then ligated into anexpression vector, which is used to transform an E. coli host based onstrain 52 (W3110 fuhA(tonA) Ion galE rpoHts(htpRts) cipP(lacIq).Transformants are first grown in LB containing 50 mg/ml carbenicillin at30° C. with shaking until an O.D.600 of 3–5 is reached. Cultures arethen diluted 50–100 fold into CRAP media (prepared by mixing 3.57 g(NH₄)₂SO₄, 0.71 g sodium citrate.2H2O, 1.07 g KCl, 5.36 g Difco yeastextract, 5.36 g Sheffield hycase SF in 500 mL water, as well as 110 mMMPOS, pH 7.3, 0.55% (w/v) glucose and 7 mM MgSO₄) and grown forapproximately 20–30 hours at 30° C. with shaking. Samples are removed toverify expression by SDS-PAGE analysis, and the bulk culture iscentrifuged to pellet the cells. Cell pellets are frozen untilpurification and refolding.

E. coli paste from 0.5 to 1 L fermentations (6–10 g pellets) isresuspended in 10 volumes (w/v) in 7 M guanidine, 20 mM Tris, pH 8buffer. Solid sodium sulfite and sodium tetrathionate is added to makefinal concentrations of 0.1M and 0.02 M, respectively, and the solutionis stirred overnight at 4° C. This step results in a denatured proteinwith all cysteine residues blocked by sulfitolization. The solution iscentrifuged at 40,000 rpm in a Beckman Ultracentifuge for 30 min. Thesupernatant is diluted with 3–5 volumes of metal chelate column buffer(6 M guanidine, 20 mM Tris, pH 7.4) and filtered through 0.22 micronfilters to clarify. The clarified extract is loaded onto a 5 ml QiagenNi-NTA metal chelate column equilibrated in the metal chelate columnbuffer. The column is washed with additional buffer containing 50 mMimidazole (Calbiochem, Utrol grade), pH 7.4. The protein is eluted withbuffer containing 250 mM imidazole. Fractions containing the desiredprotein are pooled and stored at 4° C. Protein concentration isestimated by its absorbance at 280 nm using the calculated extinctioncoefficient based on its amino acid sequence.

The proteins are refolded by diluting the sample slowly into freshlyprepared refolding buffer consisting of: 20 mM Tris, pH 8.6, 0.3 M NaCl,2.5 M urea, 5 mM cysteine, 20 mM glycine and 1 mM EDTA. Refoldingvolumes are chosen so that the final protein concentration is between 50to 100 micrograms/ml. The refolding solution is stirred gently at 4° C.for 12–36 hours. The refolding reaction is quenched by the addition ofTFA to a final concentration of 0.4% (pH of approximately 3). Beforefurther purification of the protein, the solution is filtered through a0.22 micron filter and acetonitrile is added to 2–10% finalconcentration. The refolded protein is chromatographed on a Poros R1/Hreversed phase column using a mobile buffer of 0.1% TFA with elutionwith a gradient of acetonitrile from 10 to 80%. Aliquots of fractionswith A280 absorbance are analyzed on SDS polyacrylamide gels andfractions containing homogeneous refolded protein are pooled. Generally,the properly refolded species of most proteins are eluted at the lowestconcentrations of acetonitrile since those species are the most compactwith their hydrophobic interiors shielded from interaction with thereversed phase resin. Aggregated species are usually eluted at higheracetonitrile concentrations. In addition to resolving misfolded forms ofproteins from the desired form, the reversed phase step also removesendotoxin from the samples.

Fractions containing the desired folded IL-22 polypeptide are pooled andthe acetonitrile removed using a gentle stream of nitrogen directed atthe solution. Proteins are formulated into 20 mM Hepes, pH 6.8 with 0.14M sodium chloride and 4% mannitol by dialysis or by gel filtration usingG25 Superfine (Pharmacia) resins equilibrated in the formulation bufferand sterile filtered.

Many of the IL-22 polypeptides disclosed herein were successfullyexpressed as described above.

Example 12

Expression of IL-22 in Mammalian Cells

This example illustrates preparation of a potentially glycosylated formof IL-22 by recombinant expression in mammalian cells.

The vector, pRK5 (see EP 307,247, published Mar. 15, 1989), is employedas the expression vector. Optionally, the IL-22 DNA is ligated into pRK5with selected restriction enzymes to allow insertion of the IL-22 DNAusing ligation methods such as described in Sambrook et al., supra. Theresulting vector is called pRK5-IL-22.

In one embodiment, the selected host cells may be 293 cells. Human 293cells (ATCC CCL 1573) are grown to confluence in tissue culture platesin medium such as DMEM supplemented with fetal calf serum andoptionally, nutrient components and/or antibiotics. About 10 μgpRK5-IL-22 DNA is mixed with about 1 μg DNA encoding the VA RNA gene[Thimmappaya et al., Cell, 31:543 (1982)] and dissolved in 500 μl of 1mM Tris-HCl, 0.1 mM EDTA, 0.227 M CaCl₂. To this mixture is added,dropwise, 500 μl of 50 mM HEPES (pH 7.35), 280 mM NaCl, 1.5 mM NaPO₄,and a precipitate is allowed to form for 10 minutes at 25° C. Theprecipitate is suspended and added to the 293 cells and allowed tosettle for about four hours at 37° C. The culture medium is aspiratedoff and 2 ml of 20% glycerol in PBS is added for 30 seconds. The 293cells are then washed with serum free medium, fresh medium is added andthe cells are incubated for about 5 days.

Approximately 24 hours after the transfections, the culture medium isremoved and replaced with culture medium (alone) or culture mediumcontaining 200 μCi/ml ³⁵S-cysteine and 200 μCi/Ml ³⁵S-methionine. Aftera 12 hour incubation, the conditioned medium is collected, concentratedon a spin filter, and loaded onto a 15% SDS gel. The processed gel maybe dried and exposed to film for a selected period of time to reveal thepresence of IL-22 polypeptide. The cultures containing transfected cellsmay undergo further incubation (in serum free medium) and the medium istested in selected bioassays.

In an alternative technique, IL-22 may be introduced into 293 cellstransiently using the dextran sulfate method described by Somparyrac etal., Proc. Natl. Acad. Sci., 12:7575 (1981). 293 cells are grown tomaximal density in a spinner flask and 700 μg pRK5-IL-22 DNA is added.The cells are first concentrated from the spinner flask bycentrifugation and washed with PBS. The DNA-dextran precipitate isincubated on the cell pellet for four hours. The cells are treated with20% glycerol for 90 seconds, washed with tissue culture medium, andre-introduced into the spinner flask containing tissue culture medium, 5μg/ml bovine insulin and 0.1 μg/ml bovine transferrin. After about fourdays, the conditioned media is centrifuged and filtered to remove cellsand debris. The sample containing expressed IL-22 can then beconcentrated and purified by any selected method, such as dialysisand/or column chromatography.

In another embodiment, IL-22 can be expressed in CHO cells. ThepRK5-IL-22 can be transfected into CHO cells using known reagents suchas CaPO₄ or DEAE-dextran. As described above, the cell cultures can beincubated, and the medium replaced with culture medium (alone) or mediumcontaining a radiolabel such as ³⁵S-methionine. After determining thepresence of IL-22 polypeptide, the culture medium may be replaced withserum free medium. Preferably, the cultures are incubated for about 6days, and then the conditioned medium is harvested. The mediumcontaining the expressed IL-22 can then be concentrated and purified byany selected method.

Epitope-tagged IL-22 may also be expressed in host CHO cells. The IL-22may be subcloned out of the pRK5 vector. The subclone insert can undergoPCR to fuse in frame with a selected epitope tag such as a poly-his taginto a Baculovirus expression vector. The poly-his tagged IL-22 insertcan then be subcloned into a SV40 driven vector containing a selectionmarker such as DHFR for selection of stable clones. Finally, the CHOcells can be transfected (as described above) with the SV40 drivenvector. Labeling may be performed, as described above, to verifyexpression. The culture medium containing the expressed poly-His taggedIL-22 can then be concentrated and purified by any selected method, suchas by Ni²⁺-chelate affinity chromatography.

IL-22 may also be expressed in CHO and/or COS cells by a transientexpression procedure or in CHO cells by another stable expressionprocedure.

Stable expression in CHO cells is performed using the followingprocedure. The proteins are expressed as an IgG construct(immunoadhesin), in which the coding sequences for the soluble forms(e.g. extracellular domains) of the respective proteins are fused to anIgG1 constant region sequence containing the hinge, CH2 and CH2 domainsand/or is a poly-His tagged form.

Following PCR amplification, the respective DNAs are subcloned in a CHOexpression vector using standard techniques as described in Ausubel etal., Current Protocols of Molecular Biology, Unit 3.16, John Wiley andSons (1997). CHO expression vectors are constructed to have compatiblerestriction sites 5′ and 3′ of the DNA of interest to allow theconvenient shuttling of cDNA's. The vector used expression in CHO cellsis as described in Lucas et al., Nucl. Acids Res. 24:9 (1774–1779(1996), and uses the SV40 early promoter/enhancer to drive expression ofthe cDNA of interest and dihydrofolate reductase (DHFR). DHFR expressionpermits selection for stable maintenance of the plasmid followingtransfection.

Twelve micrograms of the desired plasmid DNA is introduced intoapproximately 10 million CHO cells using commercially availabletransfection reagents Superfect® (Quiagen), Dosper® or Fugen®(Boehringer Mannheim). The cells are grown as described in Lucas et al.,supra. Approximately 3×10⁻⁷ cells are frozen in an ampule for furthergrowth and production as described below.

The ampules containing the plasmid DNA are thawed by placement intowater bath and mixed by vortexing. The contents are pipetted into acentrifuge tube containing 10 mLs of media and centrifuged at 1000 rpmfor 5 minutes. The supernatant is aspirated and the cells areresuspended in 10 mL of selective media (0.2 μm filtered PS20 with 5%0.2 μm diafiltered fetal bovine serum). The cells are then aliquotedinto a 100 mL spinner containing 90 mL of selective media. After 1–2days, the cells are transferred into a 250 mL spinner filled with 150 mLselective growth medium and incubated at 37° C. After another 2–3 days,250 mL, 500 mL and 2000 mL spinners are seeded with 3×10⁵ cells/mL. Thecell media is exchanged with fresh media by centrifugation andresuspension in production medium. Although any suitable CHO media maybe employed, a production medium described in U.S. Pat. No. 5,122,469,issued Jun. 16, 1992 may actually be used. A 3L production spinner isseeded at 1.2×10⁶ cells/mL. On day 0, the cell number pH ie determined.On day 1, the spinner is sampled and sparging with filtered air iscommenced. On day 2, the spinner is sampled, the temperature shifted to33° C., and 30 mL of 500 g/L glucose and 0.6 mL of 10% antifoam (e.g.,35% polydimethylsiloxane emulsion, Dow Corning 365 Medical GradeEmulsion) taken. Throughout the production, the pH is adjusted asnecessary to keep it at around 7.2. After 10 days, or until theviability dropped below 70%, the cell culture is harvested bycentrifugation and filtering through a 0.22 μm filter The filtrate waseither stored at 4° C. or immediately loaded onto columns forpurification.

For the poly-His tagged constructs, the proteins are purified using aNi-NTA column (Qiagen). Before purification, imidazole is added to theconditioned media to a concentration of 5 mM. The conditioned media ispumped onto a 6 ml Ni-NTA column equilibrated in 20 mM Hepes, pH 7.4,buffer containing 0.3 M NaCl and 5 mM imidazole at a flow rate of 4–5ml/min. at 4° C. After loading, the column is washed with additionalequilibration buffer and the protein eluted with equilibration buffercontaining 0.25 M imidazole. The highly purified protein is subsequentlydesalted into a storage buffer containing 10 mM Hepes, 0.14 M NaCl and4% mannitol, pH 6.8, with a 25 ml G25 Superfine (Pharmacia) column andstored at −80° C.

Immunoadhesin (Fc-containing) constructs are purified from theconditioned media as follows. The conditioned medium is pumped onto a 5ml Protein A column (Pharmacia) which had been equilibrated in 20 mM Naphosphate buffer, pH 6.8. After loading, the column is washedextensively with equilibration buffer before elution with 100 mM citricacid, pH 3.5. The eluted protein is immediately neutralized bycollecting 1 ml fractions into tubes containing 275 μL of 1 M Trisbuffer, pH 9. The highly purified protein is subsequently desalted intostorage buffer as described above for the poly-His tagged proteins. Thehomogeneity is assessed by SDS polyacrylamide gels and by N-terminalamino acid sequencing by Edman degradation.

Many of the IL-22 polypeptides disclosed herein were successfullyexpressed as described above.

Example 13

Expression of IL-22 in Yeast

The following method describes recombinant expression of IL-22 in yeast.

First, yeast expression vectors are constructed for intracellularproduction or secretion of IL-22 from the ADH2/GAPDH promoter. DNAencoding IL-22 and the promoter is inserted into suitable restrictionenzyme sites in the selected plasmid to direct intracellular expressionof IL-22. For secretion, DNA encoding IL-22 can be cloned into theselected plasmid, together with DNA encoding the ADH2/GAPDH promoter, anative IL-22 signal peptide or other mammalian signal peptide, or, forexample, a yeast alpha-factor or invertase secretory signal/leadersequence, and linker sequences (if needed) for expression of IL-22.

Yeast cells, such as yeast strain AB110, can then be transformed withthe expression plasmids described above and cultured in selectedfermentation media. The transformed yeast supernatants can be analyzedby precipitation with 10% trichloroacetic acid and separation bySDS-PAGE, followed by staining of the gels with Coomassie Blue stain.

Recombinant IL-22 can subsequently be isolated and purified by removingthe yeast cells from the fermentation medium by centrifugation and thenconcentrating the medium using selected cartridge filters. Theconcentrate containing IL-22 may further be purified using selectedcolumn chromatography resins.

Many of the IL-22 polypeptides disclosed herein were successfullyexpressed as described above.

Example 14

Expression of IL-22 in Baculovirus-Infected Insect Cells

The following method describes recombinant expression of IL-22 inBaculovirus-infected insect cells.

The sequence coding for IL-22 is fused upstream of an epitope tagcontained within a baculovirus expression vector. Such epitope tagsinclude poly-his tags and immunoglobulin tags (like Fe regions of IgG).A variety of plasmids may be employed, including plasmids derived fromcommercially available plasmids such as pVL1393 (Novagen). Briefly, thesequence encoding IL-22 or the desired portion of the coding sequence ofIL-22 such as the sequence encoding the extracellular domain of atransmembrane protein or the sequence encoding the mature protein if theprotein is extracellular is amplified by PCR with primers complementaryto the 5′ and 3′ regions. The 5′ primer may incorporate flanking(selected) restriction enzyme sites. The product is then digested withthose selected restriction enzymes and subcloned into the expressionvector.

Recombinant baculovirus is generated by co-transfecting the aboveplasmid and BaculoGold™ virus DNA (Pharmingen) into Spodopterafrugiperda (“Sf9”) cells (ATCC CRL 1711) using lipofectin (commerciallyavailable from GIBCO-BRL). After 4–5 days of incubation at 28° C., thereleased viruses are harvested and used for further amplifications.Viral infection and protein expression are performed as described byO'Reilley et al., Baculovirus expression vectors: A Laboratory Manual,Oxford: Oxford University Press (1994).

Expressed poly-his tagged IL-22 can then be purified, for example, byNi²⁺-chelate affinity chromatography as follows. Extracts are preparedfrom recombinant virus-infected Sf9 cells as described by Rupert et al.,Nature, 362:175–179 (1993). Briefly, Sf9 cells are washed, resuspendedin sonication buffer (25 mL Hepes, pH 7.9; 12.5 mM MgCl₂; 0.1 mM EDTA;10% glycerol; 0.1% NP-40; 0.4 M KCl), and sonicated twice for 20 secondson ice. The sonicates are cleared by centrifugation, and the supernatantis diluted 50-fold in loading buffer (50 mM phosphate, 300 mM NaCl, 10%glycerol, pH 7.8) and filtered through a 0.45 μm filter. A Ni²⁺-NTAagarose column (commercially available from Qiagen) is prepared with abed volume of 5 mL, washed with 25 mL of water and equilibrated with 25mL of loading buffer. The filtered cell extract is loaded onto thecolumn at 0.5 mL per minute. The column is washed to baseline A₂₈₀ (withloading buffer, at which point fraction collection is started. Next, thecolumn is washed with a secondary wash buffer (50 mM phosphate; 300 mMNaCl, 10% glycerol, pH 6.0), which elutes nonspecifically bound protein.After reaching A₂₈₀ baseline again, the column is developed with a 0 to500 mM Imidazole gradient in the secondary wash buffer. One mL fractionsare collected and analyzed by SDS-PAGE and silver staining or Westernblot with Ni²⁺-NTA-conjugated to alkaline phosphatase(Qiagen). Fractionscontaining the eluted His₁₀-tagged IL-22 are pooled and dialyzed againstloading buffer.

Alternatively, purification of the IgG tagged (or Fe tagged) IL-22 canbe performed using known chromatography techniques, including forinstance, Protein A or protein G column chromatography.

Many of the IL-22 polypeptides disclosed herein were successfullyexpressed as described above.

Example 15

Preparation of Antibodies that Bind IL-22

This example illustrates preparation of monoclonal antibodies which canspecifically bind IL-22.

Techniques for producing the monoclonal antibodies are known in the artand are described, for instance, in Goding, supra. Immunogens that maybe employed include purified IL-22, fusion proteins containing IL-22,and cells expressing recombinant IL-22 on the cell surface. Selection ofthe immunogen can be made by the skilled artisan without undueexperimentation.

Mice, such as Balb/c, are immunized with the IL-22 immunogen emulsifiedin complete Freund's adjuvant and injected subcutaneously orintraperitoneally in an amount from 1–100 micrograms. Alternatively, theimmunogen is emulsified in MPL-TDM adjuvant (Ribi ImmunochemicalResearch, Hamilton, Mont.) and injected into the animal's hind footpads. The immunized mice are then boosted 10 to 12 days later withadditional immunogen emulsified in the selected adjuvant. Thereafter,for several weeks, the mice may also be boosted with additionalimmunization injections. Serum samples may be periodically obtained fromthe mice by retro-orbital bleeding for testing in ELISA assays to detectanti-IL-22 antibodies.

After a suitable antibody titer has been detected, the animals“positive” for antibodies can be injected with a final intravenousinjection of IL-22. Three to four days later, the mice are sacrificedand the spleen cells are harvested. The spleen cells are then fused(using 35% polyethylene glycol) to a selected murine myeloma cell linesuch as P3X63AgU.1, available from ATCC, No. CRL 1597. The fusionsgenerate hybridoma cells which can then be plated in 96 well tissueculture plates containing HAT (hypoxanthine, aminopterin, and thymidine)medium to inhibit proliferation of non-fused cells, myeloma hybrids, andspleen cell hybrids.

The hybridoma cells will be screened in an ELISA for reactivity againstIL-22. Determination of “positive” hybridoma cells secreting the desiredmonoclonal antibodies against IL-22 is within the skill in the art.

The positive hybridoma cells can be injected intraperitoneally intosyngeneic Balb/c mice to produce ascites containing the anti-IL-22monoclonal antibodies. Alternatively, the hybridoma cells can be grownin tissue culture flasks or roller bottles. Purification of themonoclonal antibodies produced in the ascites can be accomplished usingammonium sulfate precipitation, followed by gel exclusionchromatography. Alternatively, affinity chromatography based uponbinding of antibody to protein A or protein G can be employed.

Example 16

Purification of IL-22 Polypeptides Using Specific Antibodies

Native or recombinant IL-22 polypeptides may be purified by a variety ofstandard techniques in the art of protein purification. For example,pro-IL-22 polypeptide, mature IL-22 polypeptide, or pre-IL-22polypeptide is purified by immunoaffinity chromatography usingantibodies specific for the IL-22 polypeptide of interest. In general,an immunoaffinity column is constructed by covalently coupling theanti-IL-22 polypeptide antibody to an activated chromatographic resin.

Polyclonal immunoglobulins are prepared from immune sera either byprecipitation with ammonium sulfate or by purification on immobilizedProtein A (Pharmacia LKB Biotechnology, Piscataway, N.J.). Likewise,monoclonal antibodies are prepared from mouse ascites fluid by ammoniumsulfate precipitation or chromatography on immobilized Protein A.Partially purified immunoglobulin is covalently attached to achromatographic resin such as CnBr-activated SEPHAROSE™ (Pharmacia LKBBiotechnology). The antibody is coupled to the resin, the resin isblocked, and the derivative resin is washed according to themanufacturer's instructions.

Such an immunoaffinity column is utilized in the purification of IL-22polypeptide by preparing a fraction from cells containing IL-22polypeptide in a soluble form. This preparation is derived bysolubilization of the whole cell or of a subcellular fraction obtainedvia differential centrifugation by the addition of detergent or by othermethods well known in the art. Alternatively, soluble IL-22 polypeptidecontaining a signal sequence may be secreted in useful quantity into themedium in which the cells are grown.

A soluble IL-22 polypeptide-containing preparation is passed over theimmunoaffinity column, and the column is washed under conditions thatallow the preferential absorbance of IL-22 polypeptide (e.g., high ionicstrength buffers in the presence of detergent). Then, the column iseluted under conditions that disrupt antibody/IL-22 polypeptide binding(e.g., a low pH buffer such as approximately pH 2–3, or a highconcentration of a chaotrope such as urea or thiocyanate ion), and IL-22polypeptide is collected.

Example 17

Drug Screening

This invention is particularly useful for screening compounds by usingIL-22 polypeptides or binding fragment thereof in any of a variety ofdrug screening techniques. The IL-22 polypeptide or fragment employed insuch a test may either be free in solution, affixed to a solid support,borne on a cell surface, or located intracellularly. One method of drugscreening utilizes eukaryotic or prokaryotic host cells which are stablytransformed with recombinant nucleic acids expressing the IL-22polypeptide or fragment. Drugs are screened against such transformedcells in competitive binding assays. Such cells, either in viable orfixed form, can be used for standard binding assays. One may measure,for example, the formation of complexes between IL-22 polypeptide or afragment and the agent being tested. Alternatively, one can examine thediminution in complex formation between the IL-22 polypeptide and itstarget cell or target receptors caused by the agent being tested.

Thus, the present invention provides methods of screening for drugs orany other agents which can affect an IL-22 polypeptide-associateddisease or disorder. These methods comprise contacting such an agentwith an IL-22 polypeptide or fragment thereof and assaying (1) for thepresence of a complex between the agent and the IL-22 polypeptide orfragment, or (ii) for the presence of a complex between the IL-22polypeptide or fragment and the cell, by methods well known in the art.In such competitive binding assays, the IL-22 polypeptide or fragment istypically labeled. After suitable incubation, free IL-22 polypeptide orfragment is separated from that present in bound form, and the amount offree or uncomplexed label is a measure of the ability of the particularagent to bind to IL-22 polypeptide or to interfere with the IL-22polypeptide/cell complex.

Another technique for drug screening provides high throughput screeningfor compounds having suitable binding affinity to a polypeptide and isdescribed in detail in WO 84/03564, published on Sep. 13, 1984. Brieflystated, large numbers of different small peptide test compounds aresynthesized on a solid substrate, such as plastic pins or some othersurface. As applied to an IL-22 polypeptide, the peptide test compoundsare reacted with IL-22 polypeptide and washed. Bound IL-22 polypeptideis detected by methods well known in the art. Purified IL-22 polypeptidecan also be coated directly onto plates for use in the aforementioneddrug screening techniques. In addition, non-neutralizing antibodies canbe used to capture the peptide and immobilize it on the solid support.

This invention also contemplates the use of competitive drug screeningassays in which neutralizing antibodies capable of binding IL-22polypeptide specifically compete with a test compound for binding toIL-22 polypeptide or fragments thereof. In this manner, the antibodiescan be used to detect the presence of any peptide which shares one ormore antigenic determinants with IL-22 polypeptide.

Example 18

Rational Drug Design

The goal of rational drug design is to produce structural analogs ofbiologically active polypeptide of interest (i.e., an IL-22 polypeptide)or of small molecules with which they interact, e.g., agonists,antagonists, or inhibitors. Any of these examples can be used to fashiondrugs which are more active or stable forms of the IL-22 polypeptide orwhich enhance or interfere with the function of the IL-22 polypeptide invivo (c.f., Hodgson, Bio/Technology, 9: 19–21 (1991)).

In one approach, the three-dimensional structure of the IL-22polypeptide, or of an IL-22 polypeptide-inhibitor complex, is determinedby x-ray crystallography, by computer modeling or, most typically, by acombination of the two approaches. Both the shape and charges of theIL-22 polypeptide must be ascertained to elucidate the structure and todetermine active site(s) of the molecule. Less often, useful informationregarding the structure of the IL-22 polypeptide may be gained bymodeling based on the structure of homologous proteins. In both cases,relevant structural information is used to design analogous IL-22polypeptide-like molecules or to identify efficient inhibitors. Usefulexamples of rational drug design may include molecules which haveimproved activity or stability as shown by Braxton and Wells,Biochemistry. 31:7796–7801 (1992) or which act as inhibitors, agonists,or antagonists of native peptides as shown by Athauda et al., J.Biochem., 113:742–746 (1993).

It is also possible to isolate a target-specific antibody, selected byfunctional assay, as described above, and then to solve its crystalstructure. This approach, in principle, yields a pharmacore upon whichsubsequent drug design can be based. It is possible to bypass proteincrystallography altogether by generating anti-idiotypic antibodies(anti-ids) to a functional, pharmacologically active antibody. As amirror image of a mirror image, the binding site of the anti-ids wouldbe expected to be an analog of the original receptor. The anti-id couldthen be used to identify and isolate peptides from banks of chemicallyor biologically produced peptides. The isolated peptides would then actas the pharmacore.

By virtue of the present invention, sufficient amounts of the IL-22polypeptide may be made available to perform such analytical studies asX-ray crystallography. In addition, knowledge of the IL-22 polypeptideamino acid sequence provided herein will provide guidance to thoseemploying computer modeling techniques in place of or in addition tox-ray crystallography.

DEPOSIT OF MATERIAL

The following materials have been deposited with the American TypeCulture Collection, 10801 University Blvd., Manassas, Va. 20110-2209,USA (ATCC):

Material ATCC Dep. No. Deposit Date DNA125185-2806 PTA-1031 Dec. 7, 1999

These deposits were made under the provisions of the Budapest Treaty onthe International Recognition of the Deposit of Microorganisms for thePurpose of Patent Procedure and the Regulations thereunder (BudapestTreaty). This assures maintenance of a viable culture of the deposit for30 years from the date of deposit. The deposits will be made availableby ATCC under the terms of the Budapest Treaty, and subject to anagreement between Genentech, Inc. and ATCC, which assures permanent andunrestricted availability of the progeny of the culture of the depositto the public upon issuance of the pertinent U.S. patent or upon layingopen to the public of any U.S. or foreign patent application, whichevercomes first, and assures availability of the progeny to one determinedby the U.S. Commissioner of Patents and Trademarks to be entitledthereto according to 35 USC § 122 and the Commissioner's rules pursuantthereto (including 37 CFR § 1.14 with particular reference to 886 OG638).

The assignee of the present application has agreed that if a culture ofthe materials on deposit should die or be lost or destroyed whencultivated under suitable conditions, the materials will be promptlyreplaced on notification with another of the same. Availability of thedeposited material is not to be construed as a license to practice theinvention in contravention of the rights granted under the authority ofany government in accordance with its patent laws.

The foregoing written specification is considered to be sufficient toenable one skilled in the art to practice the invention. The presentinvention is not to be limited in scope by the construct deposited,since the deposited embodiment is intended as a single illustration ofcertain aspects of the invention and any constructs that arefunctionally equivalent are within the scope of this invention. Thedeposit of material herein does not constitute an admission that thewritten description herein contained is inadequate to enable thepractice of any aspect of the invention, including the best modethereof, nor is it to be construed as limiting the scope of the claimsto the specific illustrations that it represents. Indeed, variousmodifications of the invention in addition to those shown and describedherein will become apparent to those skilled in the art from theforegoing description and fall within the scope of the appended claims.

1. A method of inhibiting Pancreatitis Associated Protein (PAP1)expression in mammalian cells, said method comprising contacting saidcells with an antibody that binds to IL-22, thereby inhibiting said PAP1expression by said cells.
 2. The method of claim 1, wherein the antibodyis a monoclonal antibody.
 3. The method of claim 1, wherein the antibodyis an antibody fragment.
 4. The method of claim 3, wherein the antibodyfragment is a Fab, Fab′, F(ab′)₂, Fv, or sFv fragment.
 5. The method ofclaim 3, wherein the antibody fragment is a single-chain antibody. 6.The method of claim 1, wherein the antibody is a humanized antibody. 7.The method of claim 1, wherein the antibody is a human antibody.
 8. Themethod of claim 1, wherein the cells are pancreatic cells.